Bruce Jenner's transition has been tough on his entire family, and that includes his step-daughter Kim Kardashian and ex-wife Kris Jenner.
In a clip from tonight's episode of Keeping up with the Kardashians: About Bruce, the first half of a two-part special, Kim stars crying while talking about her parents.
Kim admits that when Bruce first told her he wanted to tell his whole story, she thought, "I'm totally going to cry. My throat [was] literally like burning."
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The 34-year-old mogul's emotional reaction wasn't really for herself but for her mom Kris. "This is really hard for her," she explains to her youngest siblings Kendall and Kylie Jenner. "It's so sad. Like, she cries all the time and it makes me really sad."
Kim adds, tearing up, "But we should really appreciate all the things she does for us, because she does a lot."
Watch the clip from KUWTK: About Bruce here:
After Bruce's 20/20 interview with Diane Saywer, Kim stepped out in support of her stepfather. "I'm really happy for him that he is living his life the way he wants to live it," she told Today co-host Matt Lauer. "And that he has found inner peace and just pure happiness. That's what life is about."
Even in that 20/20 interview, Bruce said his daughter has been supportive -- but never that it's been easy for any of the Kardashians.
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The About Bruce special was filmed before Diane Sawyer's interview. Kris did not give a comment to 20/20 -- the Kardashian matriarch claims she wasn't contacted -- but has since publicly shown support for her ex-husband.
Kris recently told ET that she wanted to do the About Bruce special because "it might be helpful to families going through the same thing and hopefully shed some light on something that might bring comfort to someone else."
Watch Kris address her critics in the video below.
KUWTK: About Bruce airs tonight and Monday on E! at 9/8c.