scott disick
Scott Disick is upset that he was not invited to Khloe Kardashian's birthday E!

Scott Disick has lashed out at ex-girlfriend Kourtney Kardashian after learning that he was not invited to Khloe Kardahsian's birthday party, telling her she is "fake".

The 34-year-old entrepreneur – who is the father to Kourtney's three children and is now dating 19-year-old Sofia Richie – becomes embroiled in an argument with his former partner in a new sneak peek of Keeping Up With The Kardashians.

Visibly upset he wasn't invited to Khloe's 34th bash, Disick said: "F**k, I didn't even get invited to her birthday," while in a heated conversation with Kourtney and her younger sister Kim Kardashian West.

He added: "And I'm family. That was really sweet. That made me feel really good."

Insinuating that it was Kourtney who made sure he wasn't invited to the celebration, he continued: "There's only one person that would have gotten me not invited and that's Kourtney. I highly doubt that Khloe was like, 'The last person I'd want at my surprise party would be Scott.'

"It's cool. Honestly, I called my sister and I hung out with her the whole night. And then actually I called my mom after and was, 'Hey mom, do you want to come over because I'm feeling a little down and lonely because the family that claims I'm still blood even though we're not together still doesn't invite me to a surprise party.' But I really felt good about it," he added.

Disick has long thought of the Kardashians as his main family since his parents have both passed away and he has no brothers or sisters.

Explaining why he wasn't invited to her sister's birthday, Kourtney explained: "I didn't want to have you coming to the birthday and be photographed going in," before backtracking the comment and claiming it was not what she "really" meant.

"I'm a little bit caught off guard. I was trying to be positive. I didn't want to say I just didn't want you there. So, if I can't say anything nice, I just won't say anything at all," she added.

Disick took the news badly, exploding with: "That's all bulls**t. It's funny to realise just how fake you really are though."

Kourtney began dating Disick in 2006 after meeting at a party in Mexico, and the pair have had a turbulent, on and off relationship over the years. Despite having three children together, the couple appear to have finished their relationship for good.

Kourtney is now dating male model Younes Bendjima while Disick has been linked to a string of women including Bella Thorne and model Ella Ross, but now appears to be in a relationship with Lionel Richie's teen daughter.

Keeping Up With the Kardashians airs Sundays at 9 p.m. ET/PT on E!

Run away with it

A post shared by Sofia Richie (@sofiarichie) on