Wife's Secret Shocks Town: She Was Born He Fire takes fireman's life and ignites legal battle between his family and widow.

Oct. 21, 2010 -- Nikki Araguz said she finally found happiness -- just as it was ripped up from underneath her.

After a difficult youth and rocky first marriage that ended in divorce, in 2007, she met a volunteer firefighter named Thomas Araguz in the tiny town of Wharton, Texas, quickly fell in love and got married.

She relished her role as a stepmom to her husband's two young sons, over whom he had joint custody. She had just launched her own magazine in Wharton and encouraged her husband to go back to school and pursue his dream of becoming a police officer. Then, tragedy struck.

The unthinkable developments would set off a chain of events that exposed a long-kept secret of Nikki's life and rocked her small Texas town.

Blaze Takes Young Fireman's Life

The devastating news came in the early morning hours of July 4, 2010. Nikki Araguz was away on a road trip visiting friends in California when she got a call from another firefighter's wife.

"She said, 'You need to come home right now. They lost Thomas in a fire at 11 o'clock last night," Nikki Araguz recalled.

While fighting a five-alarm blaze that broke out at a local egg farm, Thomas Araguz was separated from the other men on his team. The fire was so intense that more than 30 departments from all around Wharton responded. It took 10 hours to finally locate Araguz's body.

In a panic, Nikki Araguz got in her car and raced home. But the life she was running back to had already been turned upside down when, just two months earlier, Thomas Araguz' ex-wife, Heather Delgado, took him to court to challenge their custody agreement.

Thomas Araguz had the boys four days a week and Delgado was unhappy with the active role Nikki Araguz had begun playing in her children's lives.

"She just tried to take over right away, with school, medical appointments, dentist appointments," Delgado said. "I would make them. She would call and cancel to set them on a date when Thomas had the boys so that she could take them."

With the help of a lawyer, Delgado started digging into Nikki Araguz's past. They found arrests for passing bad checks and struggles with drugs and alcohol, but it was Araguz's birth certificate that would yield the bombshell no one saw coming.

Delgado discovered that Nikki Araguz was actually born Justin Grahm Purdue -- a man.

CLICK HERE to see photos of Nikki through the years.

Transgender Transformation: Born Justin, Now Nikki

Since the age of four or five, Nikki Araguz, born Justin Grahm Purdue, recalled feeling different from other little boys. Unlike his peers, Justin had no interest in boyish clothing or games. Instead, he gravitated to traditionally feminine activities, like playing with Barbies and dress-up, which led to constant bullying on the playground.

"They would always question me, 'Why is your brother a faggot?'" Justin's sister Vanessa Ball recalled. "I was like, 'Well, that's my brother and I love him and if you can't accept that, then I don't want to be your friend."

Justin's internal struggles continued into adolescence as the physical differences between him and other boys seemed to be getting more pronounced -- something his friends had noticed.

"When we all started developing and growing up, Justin had round shoulders. Justin had hips, a svelte waist and figure, a walk that matched, and a voice that didn't change to a masculine voice," said Rene Huff, a high school friend.

It wasn't long before Justin began living a double life, going to school dressed as a boy, but changing into girl's clothes as soon as he got out. He had a small group of female friends who knew about his alter ego and supported him.

"I remember we would get in her car, and she would put her girl clothes on, and you know, maybe a wig and lipstick, and off we would go," said Nicole Haagensson, another school friend.

CLICK HERE to see photos of Nikki through the years.

After high school, Justin went to his mother, Sheri Bockelman, and told her that from now on he would be living as a girl full time.

"She said, 'I want to dress like a girl,'" Bockelman recalled. "And I said, 'OK.' And she went into her bedroom and put on this black dress and her high heels, and her makeup, and she came out here. And I'm going, 'OK, now I see what they're all seeing."

Life as Nikki

Justin took on the name Nikki, inspired by her fascination with a long time back-up singer of her idol Madonna.

While Nikki Purdue had no trouble fooling men at bars, underneath these flirtations was always the fear of how men would respond to discovering Nikki was actually male.

Fear was something that Nikki herself had grown accustomed to living with. Several years earlier, she said she was assaulted by a stranger in a restroom. She believes the assault resulted in an HIV positive diagnosis and led her down a path of recklessness.

"I thought my life would be over in two years," she said. "I lived hard and I lived fast because I was scared I was going to die."

Nikki Purdue spent her late teens and early 20s overindulging at bars and was arrested for both theft and driving while intoxicated.

In 1996, she made her female persona official by legally changing her name from Justin Graham Purdue to Nikki Paige Purdue.

She was no longer satisfied with pretending. She wanted to be a woman and saw surgery as her only option. The price tag of such a procedure put it out of reach at the time, but it would remain a dream.

In First Marriage, Nikki Purdue Comes Clean About Gender

Shortly after changing her name at 20 years-old, Purdue met Emilio Mata. Although he was 18 years older than her, she agreed to go on a date with him. Quickly, she quickly realized she was falling for Mata and had to tell him the truth about herself.

"I knew I wasn't going to get involved with anyone unless I was brutally honest," she said. "I said on the phone one night I was born a boy. He said, 'You're joking. I don't believe you. You're just trying to blow me off.' I'm like, 'No. I wish I was joking.'"

She also told Mata she was HIV positive. After the initial shock wore off, she says he was completely accepting of her and within a few weeks the couple moved in together. In October 1999, they wed.

For the first five years, the marriage was good, she said, but even then the relationship was strained by continued substance abuse and scrapes with the law. She acknowledged that as the years passed her life began spinning totally out of control.

"I needed someone who was going to ground me and unfortunately Emilio couldn't ground me," she said.

In 2007, Nikki Mata was arrested and charged with felony possession of a controlled substance.

"I did not receive drug charges until the very end of our relationship," she said. "Literally, that was the breaking point."

Nikki Turns to God, Meets Future Husband

The couple divorced in October 2007. With her life in shambles, Nikki said she turned to God.

"When I spent two weeks in the Wharton County Jail with a Bible, I realized how important it was to pull myself together," she said. "So, I got out of jail and grabbed hold of God, quickly."

She began attending church regularly. There, she met Thomas Araguz and was instantly attracted to him.

Having both recently gotten out of bitter divorces, the two were apprehensive at first about pursuing a relationship, she said. But after a few innocent dates, which included her meeting his two sons, she knew the relationship was progressing.

"We were quickly, obviously developing a relationship that required the same level of honesty that I gave Emilio," she said. "What I said was I have a birth defect and it could be identified as being transgendered. And he was like, 'What are you talking about?'"

She said she explained to her future husband that she was born a male and that he asked to see her body. As with Mata, she said she also revealed to Araguz that she was HIV positive.

She said he accepted her and their relationship continued to progress. The couple married in the summer of 2008 and two months later her dream of physically becoming a woman finally came true.

With the $18,500 cost saved, Nikki Araguz flew to Colorado for sexual reassignment surgery. She said her husband knew about the procedure and fully supported her.

When she returned from Colorado, she said it was her husband who nursed her through several weeks of recovery. The couple then was finally able to be intimate in the way Nikki Araguz had always dreamed of.

"I had a new opportunity with my husband, to make love to him as a full woman," she said. "It was like we were built for each other physically. It was the most beautiful experience of my entire life."

Family of Firefighter Slaps Widow With Lawsuit

In April 2010, just two months before his tragic death, Thomas Araguz was in court with his ex-wife Heather Delgado looking to renegotiate their custody agreement.

While being deposed under oath, he was asked if he had ever seen his wife's birth certificate and: "Would it surprise you if it said 'male' on her birth certificate?" He replied, "Yes," and went on to testify that he was not aware of any change his wife had made to her anatomy and that he had no knowledge she had ever gone by the name Justin.

Nikki Araguz said her husband never told anyone in his conservative family about her being transgender because he worried they would not understand. She said he went into the custody deposition prepared to lie when asked about her gender, fearing honesty would mean losing his children.

But those answers now are being used against Nikki Araguz in a lawsuit filed by her husband's family.

Since Thomas Araguz died in the line of duty, there are death benefits totaling as much as $1 million to be claimed by his surviving heirs. The lawsuit attempts to block Nikki Araguz from collecting her share of that money, alleging he never knew she was born male.

Under Texas law, gender is determined at birth and same sex marriage is not recognized, so according to the Araguz family attorneys, the person known as Nikki Araguz misrepresented herself and never should have been permitted to marry Thomas Araguz.

"In the most basic sense, the courts have said that you are what you're born as," said Chad Ellis, the attorney representing Thomas Araguz's mother, Simona Longoria. "In this case, Nikki was born male. So because Nikki is and always will be male in the state of Texas, the marriage is void as a matter of law."

The case currently is making its way through the legal system and it could be several months before a decision is handed down.

While the issue of what exactly Thomas Araguz knew about his wife's history may have little legal relevance, for the two sides locked in this battle, it seems critically important.

Longoria insists her son was blindsided by the revelations that came out of the custody deposition. But Nikki Araguz argues just as passionately that she had no secrets from her husband and that this case is about basic civil rights.

"This is all about my husband being gone from me and the equal right of mine and Thomas to be married," she said. "That's what it's all about."