Jordyn Woods and Kylie Jenner. (Picture: Instagram/KylieJenner)

Jordyn Woods is "devastated" by how her "entire world has flipped upside down" after she kissed Khloe Kardashian's boyfriend Tristan Thompson.

The 21-year-old model - who is best friends with Kylie Jenner - has been cut off by the Kardashian / Jenner family after she allegedly made out with Tristan, who is the father of Khloe's daughter True, 10 months, at a recent house party.

A source told Entertainment Tonight: "She's devastated and can't believe how her entire world has flipped upside down so fast. She knows making out with Tristan was wrong. Jordyn has always considered herself a member of the Kardashian-Jenner family and has tried to apologise to the family, especially Khloe and Kylie. The family doesn't want anything to do with her right now as the whole incident is too fresh. No one is sure what the future holds for them having Jordyn in their life."

It comes after a source revealed Kylie is "very torn" on how to handle the situation with Jordyn and Tristan as the whole family want to cut her "off" now.

A source said: "The whole family is writing Jordyn off. [Kylie's been] in denial for days. She is very torn on how to handle the situation. Khloe is more disappointed that someone so close to their family would betray her. She can't believe it."

Khloe - who has had to deal with the pain of being cheated on before after Tristan was seen getting close to another woman just days before she gave birth to their daughter True 10 months ago - is "shocked" by Jordyn's betrayal.

An insider added: "She heard it from multiple people and doesn't believe him for a second. She is angry more than she is sad. And she's shocked Jordyn would do this. Of all the guys in the world, she can't fathom why Jordyn would make a decision like this. Khloe is reliving the worst kind of betrayal and pain all over again."