Updated

Kim Kardashian is fuming over her sister Khloe's cheating boyfriend.

The reality star addressed Tristan Thompson cheating on a then-pregnant Khloe Kardashian just days before her younger sister gave birth to their baby girl, True, in a sneak peek of Kim's Monday appearance on the "Ellen DeGeneres Show."

A clearly uncomfortable DeGeneres asked Kim how she felt about Thompson's cheating.

"Poor Khloe," Kim said. "Like, I don’t even know how to describe it besides it’s just so f—ed up."

She added, "We really were rooting for Khloe. And we still are. She's so strong and she’s doing the best that she can. It’s a really sad situation, all over."

The mom-of-three said she doesn't want to say too much for the sake of her new niece.

"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," she shared. "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 so messed up."

DeGeneres also asked the beauty mogul about her husband Kanye West's recent return to Twitter where he ranted about his support of Trump.

"I didn't even know he got his Twitter again until I started seeing tweets come in from other people retweeting them and I was like, 'Wait, is this real?'" Kardashian recalled.

"And then at night he came in and was like, 'Did you see my tweets?' And I was like, I did see your tweets.' And I followed him back."

Kardashian's full interview airs Monday on the "Ellen DeGeneres Show."