In a sneak-peek release of her upcoming appearance on The Ellen DeGeneres Show, Kim discussed the latest headlines involving her sister Khloe, who welcomed a baby girl with Tristan on April 12, just two days after allegations surfaced he had been unfaithful to her for months with multiple women.
Earlier this month, the Daily Mail published a video of Tristan, 27, appearing to make out with a mystery brunette at a club in New York City.
The Shade Room also posted photos of Tristan and what appeared to be the same woman walking into the Four Seasons hotel in NYC on April 8. The brunette was caught on camera leaving the hotel hours later with her Louis Vuitton overnight bag.
"We really were rooting for Khloe. And we still are," Kim said. "She's so strong and she's doing the best that she can. It's a really sad situation, all over."
To make matters worse for Tristan, TMZ recently posted a surveillance tape showing him making out with one woman and motorboating another at a Washington, D.C. hookah lounge in October 2017, when Khloe, 33, was three months along into her pregnancy.
But for the sake of her niece, who is just about two weeks old, Kim admitted to Ellen she's going to play nice to the best of her ability.
"I kind of made this rule with my brother [Rob Kardashian] -- if there's a baby involved, I'm going to keep it cute and keep it classy and not talk too bad," Kim explained.
"Well, I'm going to try not to say anything so negative because one day, True is going to see this and you know, it's just, it's so messed up."
It remains to be seen whether Khloe will stay with Tristan long-term or leave him and move back to Los Angeles to be with her friends and family. Khloe has made it known she's madly in love with Tristan, but is her love unconditional?
A source told People earlier this week Khloe is staying put at Tristan's home in Cleveland, Ohio "indefinitely" and she's "delaying that conversation" about whether to forgive and forget her boyfriend's actions "until she's ready."
One insider said Khloe "isn't ready to give up on her relationship with Tristan" but she's still "very torn" and "doesn't want to make a decision right now."
The NBA basketball star, however, is reportedly apologetic, remorseful and wants the Revenge Body host to give him another chance.
Prior to getting involved with Khloe in September 2016, Tristan dated Jordan Craig, whom he allegedly split from in mid-2016 when she was pregnant with the couple's one-year-old Prince Oliver.