Khloe Kardashian stepped out for the first time since it was revealed that her babys father, NBA star Tristan Thompson, was cheating on her with sister Kylie's best friend Jordyn Woods.

And Khloe did not look like she's taking the news well.

Khloe attended a party for clothing brand PrettyLittleThings, with good friends Larsa Pippen and Malika Haqq.

But you could tell that she was distracted, as she barely smiled in any of the pictures. And in those where she smiled - you could see that the smile was forced. 

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Khloe's friends and her sisters are all supporting her, and have formed a unified front against Tristan and Jordyn. According to multiple sources, Jordyn was kicked out of Kylie Jenner's guest house - where she's been living now for the past year. 

Sources connected to Jordyn told TMZ that the 21-year-old will be moving out of Kylie's Hidden Hills mansion and in with her mom. We're told the decision to move out was Jordyn's.

As for Khloe ... the sources say she's devastated over the split with Tristan, but is trying her best to keep a brave face for her daughter, family and friends.

TMZ broke the story ... Khloe split with Tristan after the NBA star allegedly hooked up with Woods at a house party in L.A. Sunday night. Kim Kardashian unfollowed both Jordyn and Thompson on Instagram Wednesday.