 -- Bruce Jenner was once hailed as the greatest athlete in the world and later became a reality television star with one of the world’s most famous families. Now, the former Olympian is revealing a secret that has caused him turmoil for decades.

“For all intents and purposes, I’m a woman,” Jenner told ABC’s Diane Sawyer in an exclusive interview that aired Friday in a special two-hour edition of ABC News’ “20/20.”

“People look at me differently. They see you as this macho male, but my heart and my soul and everything that I do in life -- it is part of me,” Jenner, 65, said. “That female side is part of me. That’s who I am.”

In hours of interviews with Sawyer in New York and California, Jenner detailed his internal struggles with being transgender, which he said he has wrestled with since childhood.

During the interview, Jenner referred to himself using male pronouns and ABC News has chosen to follow his lead, though he also referred to himself as “Bruce” and “her.”

“I look at it this way—Bruce always telling a lie. He’s lived a lie his whole life about who he is. And I can’t do that any longer,” Jenner said.

“My brain is much more female than it is male,” he added. “It’s hard for people to understand that, but that’s what my soul is.”

In the late 1950s, during the Eisenhower era, Jenner said he was about 8 or 9 years old when he did something new: put on a dress from his mother’s or sisters’ closet when she was out of the house.

“I marked the closet so when I put it back I could put it all back, everything back in the exact same spot so I wouldn’t get caught,” Jenner said. “And, at the time, I didn’t know why I was doing it besides it just made me feel good.”

Cross dressing became a part of Jenner’s adult life as well. He described trips on the road during his time as a motivational speaker where the anonymity of a hotel room provided an ideal venue for trying to express what he felt within.

“I’d literally go up into the hotel room, change [into women’s] clothes, and walk around,” Jenner said.

For decades, Jenner’s ex-wives and sister kept the secret of his gender identity struggle as the only people who knew. The circle expanded recently when Jenner told his mother and his 10 children. Jenner has six biological children – Burt, Cassandra, Brandon, Brody, Kendall and Kylie -- and four step children -- Kourtney, Kim, Khloe and Rob Kardashian.

“They all cried. Mainly because they didn’t want anybody to hurt dad,” Jenner said. “They are very protective of me.”

Bruce Jenner’s third child Brandon Jenner told Sawyer during the interview with “20/20” that he used to beam with pride when a stranger asked if his dad was the hero champion of the Olympics.

And now?

“I’m just honored and more proud than ever to be a part of the family,” Brandon said.

Bruce Jenner has told his children they can still call him “dad,” but Jenner is not yet sharing the female name he has chosen for himself, joking that the only decision that has been made is that it won’t start with “K.”

“She’s definitely a Jenner,” the Olympian joked.

Jenner says he has undergone cosmetic facial surgeries over the years and took the female hormone estrogen for five years in the late 1980s. Jenner has been back on hormones for the past year and a half.

At this point, Jenner is unsure of what the future holds in terms of other surgeries.

“As of now, I have all the male parts and all that kind of stuff, so in a lot of ways we’re different, okay?” Jenner said to Sawyer during the interview. “But we still identify as female. And that’s very hard for Bruce Jenner to say. Because why? I don’t want to disappoint people."

Jenner said he spoke with Laverne Cox of ‘Orange is the New Black’ fame, and said that he admires her advocacy work and she has given him advice about his public transition.

“I would like to work with this community to get this message out,” Jenner said. “They know a lot more than I know ... I am not a spokesman for the community.”

Experts and Jenner explain that there is a difference between gender identity and sexuality, and the thrice-married Jenner revealed that he has only been attracted to women. Jenner said that each wife, including reality TV star and Kardashian matriarch Kris Jenner, knew about some aspects of his struggle.

ABC News reached out to Kris Jenner for this report, but she declined to comment.

In a statement to ABC News, Jenner’s first wife, Chrystie Scott said, “Someone who has lived 65 years of his life as the wrong gender has every right to live the last quarter of his life as his authentic self. I support him and so hope the world can too. I pray for his happiness for the rest of his journey.”

Linda Thompson, Jenner’s second wife, told ABC News in a statement, “Bruce has always had my loyalty, even if he wasn’t aware of it. I support his courage and commitment to this new chapter of his life. My hope is that his transition will inspire others who struggle with their identities, and my prayer is that humanity has evolved and been educated enough to exercise kindness toward those we may perceive as ‘different.'"

The big focus for Jenner now is the path forward, while also hoping to do some good by raising awareness in the process.

“We’re going to make a difference in the world with what we’re doing,” he said. “And if the whole Kardashian show and reality television gave me that foothold into that world—to be able to go out there and really do something good, I’m all for it. I got no problem with that.”

There are an estimated 700,000 transgender people in the U.S. living in a society filled with discrimination, misunderstanding, suicide and danger, according to the Williams Institute at the University of California-Los Angeles.

“I just can’t pull the curtain any longer,” Jenner said. “I’ve built a nice little life, I just can’t—again, Bruce lives a lie. She is not a lie. I just can’t do it anymore.”

“If I die, which, I could be diagnosed next week with cancer -- and boom you’re gone,” Jenner said. “I would be so mad at myself that I didn’t explore that side of me. You know? And I don’t want that to happen."

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