The former Olympian revealed during his sit-down interview with Diane Sawyer that the 30-year-old E! star is the one who has been taking his news the hardest, which was quite the surprise.
(At this time, Bruce Jenner has not chosen to publicly identify as a woman and so E! News will continue to refer to him as Bruce and use male pronouns, until he indicates otherwise.)
"You would think out of all of the kids, Khloé is the most fun, open-minded...and that's not the case with Khloé. She's very emotional," Jenner told Sawyer. "She's had the toughest time with it. Because she's had a lot of losses in her life. She lost her father at a young age. He died suddenly, cancer. You know, Lamar [Odom] had his issues."
The interview then cut to an old clip of Koko and Bruce having a heart-to-heart on Keeping Up With the Kardashians.
"You're someone in my life that I've known since I was 5 and has been an incredibly strong male figure in my life, which we don't have many of," she said to her stepfather. "You're just such a strong man in that way, which you deserve a lot of credit for and I don't think you get."
Bruce added during the interview, "She feels like there's this massive, my whole life is falling apart, you know. It's my dad. And I try to explain. I can't argue that point but I'm not going anywhere. I'm still going to be there for you."
Regardless, Khloé took to Twitter to show her stepdad support after watching the 2-hour special tonight. "Just finished watching the #BruceJennerInterview with the family. Bruzer, I'm soooo proud of you! Dads really are heros."