Leah Remini on Her Break With the Church of Scientology: 'I Wanted to Be The One to Say It' Former "King of Queens" star sat down for an exclusive interview with "20/20."

 -- Leah Remini spoke for the first time in an exclusive interview with ABC News “20/20” about what her life was like inside the Church of Scientology, as well as how Tom Cruise and the backlash she faced from the Church after his 2006 wedding to Katie Holmes were factors in her breaking with the Church.

The former “King of Queens” star, who publicly severed ties with the Church in 2013, is the most high-profile celebrity to leave Scientology and go public with her criticisms. She spoke with “20/20” about her new memoir, “Troublemaker: Surviving Hollywood and Scientology,” and why she is no longer a member of the Church she served for 30 years.

“I know what my former Church-- how they deal with people who tell their story,” Remini told “20/20.” “And so I wanted to be the one to say it.”

This week, members of the Church of Scientology delivered multiple documents and emails and made numerous phone calls to ABC News containing highly critical statements about Leah Remini, calling her a liar, “self-absorbed, rude and embarrassing,” and saying she is attempting to “rewrite the truth” in order to sell her new book. Read the Church's full statement to ABC News regarding the interview HERE.

This is her side of the story:

How Leah Remini Became Involved in the Church of Scientology

Leah Remini grew up in the tight-knit Italian neighborhood of Bensonhurst in Brooklyn, New York.

“I always felt like I was kind of an outsider because I didn’t have the right things,” Remini said. “I didn’t have a Cadillac. I didn’t have, you know, plastic on my furniture. That was the right way to be, if you were Italian.”

Her parents divorced when she was 7 years old. Her mother Vicki Marshall, searching for meaning, became deeply involved in Scientology, the religion founded by science fiction writer L. Ron Hubbard.

Vicki worked in the Scientology building in Times Square and said her understanding of Scientology’s goal is “to free mankind, to make a sane world.” She said she believed that she was “benefiting the planet” by working for the Church and that it would help her children in the long run.

“What was told to me … [was] look at what you’re doing for the world, this is more important than… your family,” Vicki said.

Eventually Vicki decided to bring her daughters, Leah and her older sister Nicole, into the Church. The girls began studying Hubbard’s teachings and learning Scientology’s unique terminology.

As a kid, this was a big deal, Remini said, because “Scientologists view children as spiritual beings.”

“You are not treated as a kid, so you are given a lot of responsibility,” she continued. “Your ego becomes extremely inflated.”

Leah Remini Joins The Sea Org as a Young Teen

When Remini was a teenager, her mother decided to enroll her and her sister in the Sea Org, the pious, uniformed, full-time religious order of the Church, and moved the family to the Church’s spiritual headquarters in Clearwater, Florida, known as the Flag Land Base.

Mike Rinder, who was once the spokesman for the Church of Scientology, is no longer a member and is now a very public critic of the Church. He said Sea Org members “are the people who have dedicated their entire lives to Scientology, who live in communal Church facilities, eat in Church facilities.”

In statements to ABC News, the Church decries Rinder as a liar, “a bitter former member” and a “professional anti-Scientologist.”

Scientologists believe in reincarnation and Sea Org members are expected to keep working every time they come back. Remini said, “They provide room and board and you work there and you sign a billion-year contract.”

Both sisters said they were housed in a run-down former motel with “roach-infested” dorms they shared with other children. Leah Remini said she had to perform long hours of serious labor.

“It could go from working in a laundry room to working industrial sanders,” Remini said.

For Remini, joining the Sea Org meant leaving traditional school in eighth grade and immersing herself in Scientology study. “It’s more your education in Scientology is pressed upon… you’re learning how to learn Scientology,” she said.

But Remini said there were other things that prevented her rise in the Sea Org ranks.

“I would try to start a mutiny because I felt we deserved better rooms,” she said.

Things came to a head, Remini said, when she and her sister were brought up on ethics charges for their involvement with boys. It was a serious violation, and Remini said Church ethics officers threatened to put both of them into the “Rehabilitation Project Force,” a place for Scientologists who step out of line.

“When you have screwed up royally in the Sea Org, it’s basically to reform you,” she said. “You have to wear black. You have to run everywhere you go. You have to call everyone ‘sir.’ … So it’s pretty severe punishment for an adult, not to mention a child.”

When Remini’s mother Vicki heard about this, she said she decided to pull the girls out of Sea Org.

The Church told ABC News in a statement that children are no longer admitted into the Sea Org, but that Remini was “dismissed … for her inability to maintain the ethical standards related to fraternization,” and that she petitioned to stay but failed. The Church added that when Remini was a member, the living conditions at the Clearwater facility conformed to Florida state health codes.

Either way, the sisters’ billion-year contracts with Sea Org were over.

Leah Remini’s Family Moves to Hollywood and Remains Active Scientologists

After a disastrous tour of duty in the Sea Org, Remini and her family moved to East Hollywood in the mid-‘80s. Despite what happened, her mother decided to keep the family deeply involved in Scientology.

“There was a big Scientology community there,” she said. “We slept on someone’s floor… we had nothing… we had a few bags of clothes.”

Leah Remini threw herself into the practice and study of Scientology, known in the Church as “moving up the Bridge to Total Freedom,” which she said, “it promotes that you're getting to high levels of awareness as a spiritual being.”

“Moving up the Bridge” involves taking a series of courses and also participating in “auditing” sessions, a sort of counseling that employs a device known as an E-Meter. The process promises to release negative emotions.

Back in the mid-‘80s, Remini said she was going through these types of sessions almost daily, which she had to pay for out of pocket. Between auditing, courses, and materials, she said that she spent “thousands and thousands, hundreds of thousands [of dollars]” over the course of her Scientology career.

Needing money, Remini said she started waitressing and doing secretarial work, but then turned to acting and comedy, in which Remini said her experience in Scientology played an important role.

“There’s tools that are... very helpful... to you in your life, to you as an actor,” she said. “I walked into a room where some people might feel, you know, cower in front of a casting director, I wasn’t.”

Leah Remini Gets Her Big Break

Remini said she had an excruciating year trying to land acting gigs. She got a lead role on the 1989 TV show, “Living Dolls,” but the show was canceled after one season. Over the ensuing years, Remini did hundreds of auditions and landed many small guest roles on TV shows, such as “Saved By The Bell,” “Cheers” and “NYPD Blue.” She even scored some leading roles in a few sitcoms, such as “Fired Up,” and the Church was taking notice. Remini was featured on the cover of Scientology’s official Celebrity magazine.

During this time, Remini met the love of her life, Angelo Pagan, one night when he was singing in a Cuban nightclub in Los Angeles. Pagan fell so hard for Remini that he got into Scientology and eventually left his wife to be with Remini.

“Had she been into Kabbalah or Buddhist, I would have done anything,” Pagan said. “Muslim? Hey, give me the Koran, let’s go. Baby, if it’s working for you, I’m in.”

Through Pagan, Remini became friends with Jennifer Lopez and her then-husband, Mark Anthony. Shortly thereafter, Remini got the call that would change her career -- she had landed the lead role of Carrie Heffernan in a new TV show called “The King of Queens.”

How Leah Remini Met Tom Cruise

The success of “The King of Queens” gave Remini fame, money and she says an increased prominence in the Church of Scientology.

Ex-Scientologist Mike Rinder said celebrities are treated “very differently” inside the Church “depending on how prominent they are.”

“The Leah Reminis and the Kirstie Alley and the John Travolta and then ultimately to the Tom Cruise, it’s a very different world that those people live in, a very different Scientology world,” Rinder said.

Remini was appearing in Scientology videos by at least 1997 and eventually she said she was rubbing shoulders with David Miscavige, the powerful head of the Church, and his wife, Shelly Miscavige.

“He [David Miscavige] is very, you know, charismatic,” Remini said. “He’s very powerful… he’s likable.”

Remini and Pagan were married in 2003 and the couple welcomed a daughter the following year, although Remini admits that she deviated from L. Ron Hubbard’s expressed preference for drug-free births.

“I got that epidural as quickly as possible,” Remini said. “I was going to attempt to do it, you know, for my Church… But you know, when you start feeling a baby coming out of your vagina, I could have-- if there was a rock I would have hit myself over the head with it.”

That same year, Remini said she made an important friend through the Church -- the world’s most famous Scientologist, Tom Cruise, who declined to comment for this report. Meeting Cruise, Remini said, “at first it’s very effusive, it’s very loving.”

“You get the laser in on your and you’re the most important thing that ever happened,” she continued. “It’s, ‘what are you doing?’ and ‘how are you doing?’ and ‘yeah, great, great, great, great, great.’”

Remini said the exposure to Cruise opened her eyes to his vast influence within the Church, an influence she says was exemplified by a call she received one night from a Church official, who she said told her that Cruise wanted her to come over and teach him salsa dancing.

When she arrived, Remini said two high-ranking Scientology officials were there with Cruise and Katie Holmes, his new girlfriend at the time.

“He was like forcibly kissing Katie and I said, ‘hey, get a fricking room,’” Remini said. “And well, I was written up for that, and I had to go into session for it.”

Remini said one of the Church officials there that night reported her comment to the Church. It’s common practice, she said, for Church members to regularly write what are called “Knowledge Reports” on one another for breaking rules. Remini said the accused then have to answer to the allegations in auditing sessions.

“You can assume if you say something that is critical to the Church, you will be written up,” Remini said. “Husband, wife, mother, daughter, it’s what the group does to regulate itself.”

Remini admits to writing Knowledge Reports herself frequently, including on her own husband. "I wrote Angelo up all the time," she said.

After that, she said she continued to spend time with Cruise but didn’t hesitate to speak up when she thought he was damaging the Church in the public view, including in 2005 when Cruise criticized Brooke Shields for using antidepressants and he argued with Matt Lauer about psychiatry during an on-air interview, as well as when he jumped on Oprah’s couch during a widely discussed television appearance in 2006.

“I’m saying, ‘I don’t think he’s becoming of a Scientologist, jumping on couches, and attacking Matt Lauer… and attacking Brooke Shields,’” Remini said. “Like… ‘What the hell is this guy doing?’ … we need to rein it in, we need to stop all this, and he just needs to be an actor.”

But after she spoke out about Cruise’s actions, Remini said she “was immediately dealt with,” saying she was taught that “the only reason you’re saying these things is because you have your own transgressions.”

“So you then become guilty,” she continued. “So being critical of Tom Cruise is being critical of Scientology itself. … You are a person who is anti-the aims and goals of Scientology. You are evil.”

Remini said she was increasingly dismayed by the fawning attention Church officials heaped upon Cruise, who was extremely close with David Miscavige.

“I would refer to him even in my own sessions, I was like, ‘you’re doing this for a frigging actor?’” Remini said. “It was so beneath what was truly important. He’s just an actor.”

Leah Remini Attends Tom Cruise’s 2006 Wedding to Katie Holmes

In 2006, Remini received an invitation to Tom Cruise’s wedding to Katie Holmes, but she says it came with the request that she bring her friends, Jennifer Lopez and Mark Anthony.

“The Church was really the one who invited them,” she said. “On Tom’s behalf.”

They agreed to attend and in her memoir, Remini writes a lot of color about the wedding, including the moment when she said Cruise serenaded his new bride with the song, “You’ve Lost That Loving Feeling,” echoing that famous moment from his movie “Top Gun.”

“We’re like, ‘that’s an interesting song to sing to your bride,” Remini told “20/20.”

The wedding would become a pivotal point in Remini’s relationship with the Church. At the wedding, where David Miscavige served as Cruise’s best man, Remini said she became annoyed by what she saw as ham-handed attempts by the Church to separate her from Lopez by having them travel in separate vehicles and sit at different tables.

“They were always trying to extract me,” she said. “I could only assume because they wanted to make Jennifer a Scientologist and maybe I was barring that road for them.”

But what really bothered her at the wedding, Remini said, was that Miscavige was there without his wife, Shelly.

“Shelly was always where David Miscavige was,” Remini said. “It was a wedding of the century… it was like, ‘where’s Shelly?”

“There’s a Sea Org member sitting next to me from David Miscavige’s office and I’d go, ‘where’s Shelly?’” she continued. “It’s such a simple thing. It’s a big wedding that the leader of the Church is here and his wife isn't. It’s getting weirder because you're making it weirder.”

The Church told ABC News in a statement that in regards to Cruise’s wedding, every claim Remini has made is not only untrue but “ridiculous and stupid.”

But Remini said she left the wedding on what she calls a mission to save Scientology, writing a Knowledge Report complaining about Church members at the wedding.

“I thought, ‘I now see where the cracks are in our Church, and it’s David Miscavige, it’s Tom Cruise.’” Remini said. “They were bringing down Scientology.”

To her dismay, Remini said she learned that numerous Scientologists had filed reports on her for being loud, late and rude, upgrading her hotel room and switching seats at the reception. In short, Remini said, they were claiming that she had “basically destroyed the wedding.”

Remini showed “20/20” a document that she claimed was a Knowledge Report from Katie Holmes.

“It starts with, ‘I was dismayed at the behavior of Leah Remini during the events leading up to our wedding ... At the wedding, the behavior as a guest, a friend ... was very upsetting,’” Remini said, reading the document.

Remini said she was sent to the Sea Org facility in Clearwater, Florida, for what she calls “reprogramming.”

“I was in an auditing room,” she said. “Basically they were just trying to get me to recant what I said, to apologize for ruining the wedding of the century.”

In response, the Church told ABC News in a statement that “Ms. Remini voluntarily went to the Church to receive religious services. Her characterizations are another example of revisionist history.”

Even after all that, Remini said she wasn’t ready to leave the Church at the time, because she said leaving means “giving up everything you have ever known and everything you have worked for your whole life.” She was also worried about having to leave her family behind. So, Remini said, “I said everything they needed to say, and once I did that, I was free to go home.”

Leah Remini Starts to Question Staying in the Church

After the wedding, Remini resumed her life as an active Scientologist. She continued taking Church courses and doing her auditing sessions, while "The King of Queens" ended its run in May 2007 after nine seasons and 207 episodes.

Later, Remini said she wrote a letter to David Miscavige, apologizing for "acting like a complete idiot at the wedding" and "I admire you for all you have done."

But in her mind, Remini said the seeds of doubt had been growing, not just about the organization but also about its cosmic theology.

One example she said was when she reached a key level of Scientology’s “Bridge to Total Freedom,” or “Operating Thetan 3,” she was at a point where she said key Church secrets about the history of the universe are revealed. In one document written by Church founder L. Ron Hubbard, he tells a story about an intergalactic warlord named Xenu.

“It was some galactic confederation,” Remini said. “There was a war and there was a volcano and they bodied, you know, they took the spirits of people and they encased them into something, into a volcano, blew them up and then those spirits are now inside of you, on you, in you, like you are made up of these things.”

When she read that, Remini said she thought, “this is some crazy s***.” Again, she said she wasn’t ready at that time to walk away from the Church.

In a statement to ABC News, the Church would not talk about their advanced scriptures, but said that “it is not unusual for a religion to have confidential scriptures and practices," adding that “the vast majority of Scientology Scripture is widely available to the general public and can be read and studied by anyone. A very small portion that deals with the most advanced levels of spiritual counseling is restricted to those parishioners who have attained the prior levels of spiritual awareness.”

While Remini struggled privately with her faith, she said she continued a cordial friendship with Tom Cruise and exchanged friendly notes, including one in which he thanked her "for being such a great Scientologist."

But in 2012, Katie Holmes publicly left Tom Cruise, and Remini said she felt vindicated.

“Yeah, I said, ‘Where’s my apology? … Do I get an apology from Tom, from David Miscavige? … do I get and validation from the Church?’” she said.

Just this week, Katie Holmes, who declined to be interviewed for this report, gave a statement to ABC News in which she neither confirmed nor denied writing that Knowledge Report about Remini but said, “I regret having upset Leah in the past and wish her only the best in the future.”

When told about Holmes' statement, Remini told ABC News that she was “touched by it.”

How Leah Remini Eventually Decided to Break With The Church of Scientology

Remini said the Tom Cruise-Katie Holmes divorce re-ignited a lot of her old anger about her grueling counseling sessions in Florida and about all of the money she says she had spent on the Church for auditing, courses and materials. She also showed “20/20” trophies she said she received for giving more than $1 million to Scientology charities.

As her frustration mounted, she said she decided to commit a serious infraction in Scientology -- she went online and began reading comments from critics of the Church.

Remini said she saw the reports of families who said they were torn apart by the Church’s practice of “disconnection” -- the shunning of ex-members by their friends and relatives still in the Church -- and allegations by former top officials who say they were punched or slapped by David Miscavige.

“I was heartbroken for myself, for my family,” Remini said. “I didn’t want these things to be true.”

Scientology has adamantly denied that Miscavige physically stuck anyone.

Remini herself had long dismissed Church critics, but then, in an abrupt about face, she reached out to Mike Rinder, a man the Church views as one of its arch enemies.

“I mean, talking to me is like, you know, sleeping with the devil,” Rinder said.

By this point, Remini said she was becoming more and more assertive about Shelly Miscavige, whom she said she still couldn’t locate or contact. She said she demanded Church officials deliver a note from her to Shelly.

“I started to say enough and I said where is Shelly? Where is Shelly? Over and over again and I wasn’t getting an answer,” Remini said.

The situation came to a head, Remini said, when the Church sent two high-ranking Scientology officials to her house, a visit that turning into an argument, and almost much more, when Remini’s husband Angelo Pagan said one of the officials called her “a bitch.”

“I grabbed him by the collar, yes,” Pagan said.

After that, Remini said she was finally ready to leave the Church. The Church told ABC News in a statement that Remini was expelled for ethical lapses, and claims she tried to stay, which Remini denies.

Either way, Remini was very concerned her family would “disconnect” from her.

“I’m ready to walk away from everybody that I’ve ever known and cut ties with my own husband, my own mother, because you don’t know what they’re going to decide,” Remini said. “Very often, my experience is people choose the Church.”

The Church told ABC News that disconnection is voluntary and “designed to help members remove themselves from abusive and hostile relationships.”

But to Remini’s relief, her mother Vicki and the rest of her family supported her decision and left the Church with her. The fact that her family came with her, “means everything,” Remini said.

Where Things Stand with Leah Remini Today

Leah Remini went public with her separation from the Church in summer 2013.

The Church’s initial public response to her departure was subdued, but then Remini filed a missing person’s report on Shelly Miscaviage, who she said hasn’t been seen in public since August 2007.

The Los Angeles Police Department investigated the claims but told ABC News they “met with the alleged missing person” and “we consider the case closed.” The Church attacked Remini’s filing of the report as a “publicity stunt.”

The open warfare between Remini and the Church escalated when Remini went on ABC’s “Dancing With the Stars” in Sept. 2013, and danced to Katy Perry’s “Roar,” a song she said she chose to send a message.

Celebrity Scientologist Kirstie Alley went on Howard Stern’s radio show in Dec. 2013 and bashed Remini, calling her a “bigot” and saying, “when you decide to blanket statement that Scientology is evil, you are my enemy."

Remini said she understood Alley’s remarks.

“Anybody who criticizes the Church is-- to cry that everybody’s a bigot towards their religion and this is religious bigotry … I was in the same position, I said similar things about people like me,” Remini said.

Just this week, as Remini guest hosted “Dancing With the Stars,” and ABC News prepared to broadcast its interview, the Church of Scientology ramped up its criticism. In one statement to ABC News, the Church said Leah Remini's "repeated ethical lapses and callous treatment of others led to an ecclesiastical review which resulted in her being expelled. She now regurgitates the tired myths the Church has repeatedly debunked, circulated by the same tiny clique of expelled former staffers bitter at having lost the positions they enjoyed before their malfeasance and unethical conduct were uncovered." Read the Church's full statement to ABC News regarding the interview HERE.

“I agree with them, I wish I too could get over 30 years of this quickly,” Remini said. “Unfortunately it’s going to take some time… [but] that’s not a shining endorsement for the Church of Scientology to say that I’m deeply flawed after 30 years of reaching the upper levels of the Church.”

When asked if she would rather see the Church disappear or just change, Remini said it was a “hard thing” to grapple with.

“I know a lot of them have been in for a long time and I know they’re good people,” she said. “It’s the policies of the Church … It’s the parishioners that have the power. It’s the parishioners that actually could effect change by just not subscribing to it.”

Two years out of the Church, Remini said her life is now better than ever and that the ordeal has reinforced the bonds within her family, bonds on display during their reality show on TLC, “It’s All Relative,” where the departure from Scientology is frequent fodder for discussion.

“At the end, I mean I don’t regret what I’ve been through,” Remini said. “I don’t regret spending my life there, because it really did teach me a lot … and because we’ve all survived it, we’re all surviving it and living life and it’s kind of like we have a gift of second chance of life.”