Kim Kardashian Was the First To Know; Caught Bruce Jenner Wearing Women's Clothes

During his emotional and much-buzzed about 20/20 interview with Diane Sawyer, Bruce Jenner revealed that Kim Kardashian was the first of the Kardashian sisters to learn of his transition — when she saw him waering women's clothes. She's also been the most supportive, he claims.

According to Jenner, Kim caught him wearing women's clothing years before he told the rest of his family and the world that he was transitioning from male to female.

"He asked her to never say anything about it so she didn't," said a source close to the family. " He just called Kim after it happened and told her to never say anything, so she respected that," continues the source. "They never spoke in depth about it."

In Jenner's interview with Sawyer, he revealed that surprisingly enough, the reality-star and wife of rapper Kanye West has been "the most accepting" of everything.

"You would think out of all the kids, Khloé's was the most fun, open-minded," Jenner said. "And that's not the case with Khloé. She's had the toughest time with it because she's had a lot of losses in her life."

Indeed, according to a source, it's Kim who has been the closest to Jenner during this time.

"They're the closest out of the Kardashians because she has been the most understanding and perhaps because she had this experience early on," the source revealed. "She's always there to listen and try to understand what he's going through."

She even spoke words of support on his behalf during a recent interview on The Today Show.

"I know it's not something you or I could really, fully understand, but I don't even think we have to," Kim said.

"I'm really happy for him that he is living his life the way he wants to live it and that he has found inner peace and just pure happiness," she said. "That's what life is about."