Kim Kardashian gave an interview to Rolling Stone recently in which she dropped several bombshells. One of the most surprising was that she said she has known that Bruce Jenner was more comfortable as a woman long before the rest of the world had a clue.

Kim said she walked in on Bruce dressed in women’s clothing one day. He was in the garage, where no one else would see.

“I was shaking,” Kim Kardashian said of her discovery. “I didn’t know if I’d just found out his deepest, darkest secret, and he was going to come after me.”

But she needn’t have worried. Kim’s phone rang about 30 minutes later. It was her stepfather on the other end.

“One day, I’ll talk to you about this. Until then, don’t tell a soul,” he made her promise.

Kim says it was eight years before it was spoken of again.

“Let’s have that talk,” Bruce said to her. He was still married to her mother at the time, and their Keeping Up with the Kardashians empire was in full swing.

Caitlyn Jenner absolutely slays in this stunning new “I Am Cait” photo http://t.co/uvhzEwulTl pic.twitter.com/RB6EcIi2ef

— BuzzFeed (@BuzzFeed) July 9, 2015

The topic did come up when Kim Kardashian was set to marry Kanye West. Television cameras were all around.

“I wasn’t sure if Bruce was going to be comfortable walking me down the aisle,” Kim Kardashian says. “He had just had his trachea shaved, so I knew something was going on.”

Kim says she was concerned about what Kanye might think.

“[Kanye] obviously moves to his own drum,” she says. “He lives his life the way he wants, a really authentic life, and he was like, ‘If you can’t be authentic and you can’t live your life, what do you have?’ ”

Now, of course, the whole world knows about Caitlyn Jenner, and she is a force in the LGBT community. But Kim Kardashian carried that secret faithfully for 12 years.

Still getting the hang of this. What do you think of the color? https://t.co/uGsVmQnLZu

— Caitlyn Jenner (@Caitlyn_Jenner) July 9, 2015