During a Thursday appearance on The Ellen DeGeneres Show, the 36-year-old Keeping Up with the Kardashians star discussed Caitlyn's memoir The Secrets of My Life, which was released April 25 and touches upon Caitlyn's relationship with her ex-wife Kris, whom she had been married to for nearly two decades.
"My heart breaks for my mom [Kris] you know, because I feel like she's been through so much and [Caitlyn] is promoting this book and she's saying all these things," Kim told host Ellen DeGeneres. "I don't think it's necessary and I just feel like it's unfair, things aren't truthful."
One of Caitlyn's claims in her memoir is that 61-year-old Kris "made her suppress her true self" during their marriage, suggesting that Kris knew about her husband's feminine desires, according to Us Weekly.
"Caitlyn is not being honest?" Ellen asked Kim on her show about the book.
"No. Not with certain things about my mom, or other things," Kim replied. "I feel like it's taken a really long time for her to be honest with herself, so I don't expect her to be honest about my mom now. But it's just so hurtful. I wish her all the success in the world, um, but not at our expense."
When asked if anyone in the Kardashian family has a relationship with Caitlyn now, Kim explained, "Well, yeah. [Kendall Jenner] and [Kylie Jenner] because that's their dad."
"And I think my mom's been so respectful for so long and always wanting Caitlyn around and always wanting to have a great relationship with Caitlyn," Kim continued, "but I think for the 'Kardashians' -- [Caitlyn] doesnt like to say that word because she said that in her book, and on Diane Sawyer, she never purposely said our name..."
Ellen interjected Kim's train of thought to point out how Kim was ironically the person who attempted to bring everyone together once Caitlyn announced her transgender transition to the world in Summer 2015 -- and now the pair doesn't have a relationship at all.
"I haven't talked to her in a couple weeks. I'll always love her. That was my stepdad for so many years. She taught me about character and so much growing up, and I just feel like I don't respect the character that she's showing now." (Us recently reported that Caitlyn's tell-all book was also the "last straw" for Kim's sister Khloe Kardashian).
Kim said, however, she'll still "always have a major love" for Caitlyn and the role she played in the reality TV star's life.
"I'm really sentimental. I think my mom's that way. And I'll never say -- you know, it's still Kendall and Kylie's dad, so I wanna be respectful, but I just feel like there's no need for a book," Kim explained.
Kim concluded when speaking of Caitlyn, "Tell your story, but don't bash other people, you know? I just think it's, like, not tasteful."
Kris and Caitlyn wed in 1991 when the former Olympian was still known as Bruce Jenner. Kris filed for divorce in September 2014.