Tristan Thompson was the target of the full wrath of the Kardashian sisters when they found out he'd cheated on Khloe AGAIN ... this time getting another woman pregnant.
Kim Kardashian was in the middle of a workout during Thursday's episode of "The Kardashians" when she first got the news -- Tristan had filed legal docs admitting to having sex with a woman named Maralee Nichols -- who claimed she was about to father Tristan's son.
In the episode, Kim immediately calls Kylie, saying, "I'm like shaking for her. My soul dies for her." Kylie asks, stunned, "Is Tristan the worst person on the planet?" From there, Kim calls Kourtney, who says Tristan's actions have been a "never-ending betrayal."
What's more ... Kim points out the night Maralee claims she and Tristan had sex was almost immediately following a 30th birthday party that Khloe threw for him.
When Khloe calls Kim back, Kim fills her in on the situation, Khloe replies, "What the f*** is this?" and the episode ends with a tease for next week.
As we reported, the baby boy did, in fact, turn out to be Tristan's ... he and Khloe are no longer together romantically -- but have seemingly been able to co-parent their daughter True together without issue.