Khloe Kardashian has reportedly split with her boyfriend Tristan Thompson after he cheated on her with her sister Kylie Jenner’s best friend, Jordyn Woods. E! and Us Weekly spoke to insiders to get the 411 on what went down, when. The pair have been dating on and off four more than two years; the last time they split up, it was because Tristan got caught cheating on her just days before she gave birth to their daughter True.

“Khloe first started hearing things on Monday,” a source tells E! News. “She wasn't sure if it was true and started to ask around. She knew it had happened for sure on Tuesday.”

“It” refers of course to reports that Tristan had cheated on her with Jordyn. When the news first broke Tuesday, Tristan tweeted-then-deleted, “FAKE NEWS.”

On Sunday night, Jordyn and Tristan reportedly hooked up after hanging together at a bar in Santa Monica. Khloe reportedly heard from a mutual pal about the hook up, and received multiple shocked texts from eyewitnesses.

It is still unclear when Khloe dumped Tristan, but he reportedly could care less.

“He doesn't even think him hooking up with Jordyn is 'bad' because him and Khloe were broken up in his mind,” a source told Us Weekly. “He just truly doesn't care.”

Khloe and Jordyn were tight too, which adds insult to injury, according to reports. But Kylie is truly devastated.

“Kylie is having a very difficult time,” a source says. “She is devastated and emotional. She doesn't want to believe this could have happened.”

“She wanted to give Jordyn a chance to explain herself,” the source added. Meanwhile, “she's shocked and confused.”

Still, despite all of the drama, Khloe kept it cool when she appeared in public Wednesday. She was snapped leaving her brother-in-law Kanye West’s office in Calabasas, California, grinning and looking gorgeous in all-white.