The way it went down is kinda weird ... there are cameras rolling on an audience screening an episode of "The Kardashians," when Tristan pops up and talks about expanding his fam with Khloe. You hear her shriek, "LIAR!!!"
Khloe then triples down in the confessional on the latest episode, calling Tristan's wistful comments about their relationship a "crock of s***."
She recalled thinking ... "I believed you and I was listening to you and I was receiving everything you said. But you're a f***ing liar!'"
As you know KK and TT have had insane drama. TMZ broke the story back in July ... they were expecting a baby via surrogate shortly after stories surfaced Tristan had a baby with a personal trainer Maralee Nichols last December. What's worse, Tristan cajoled Khloe into having a second baby, knowing Nichols was pregnant with his baby.
The tough thing to navigate now ... co-parenting around hard feelings. At least she has a sister who more than understands that dilemma.