Now this is a rumor that is surely going to shock the entire Kardashian family. There's a new report that suggests Scott Disick might have cheated on his long-term girlfriend Kourtney Kardashian with Hollywood socialite Kimberly Stewart.

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According to the Daily Mail on Friday, eyewitnesses say that Scott supposedly "hooked up" with Kourtney's old high school friend, Kimberly. And unfortunately, Scott is regretting his "multiple romps" with the blonde beauty.

A source told the publication, "He feels like an a**hole. He was trying to get Kourtney back and was hoping she didn't find out."

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What's more, Kimberly feels bad about the hook-ups too, as the insider says that she was "overcome" by Scott's charming personality.

"Kimberly knew it was wrong, but couldn't help herself," the insider added.

If that weren't enough, there's another rumor that says Kourtney might have cheated on Scott too, before discovering that she was pregnant last year.

According to Hollywood Life last Wednesday, rumors are running wild that Kourtney might have had a fling before she discovered she was pregnant with Reign. Even though she and Scott never tied the knot, the couple had been in a long term relationship for years while living and raising their two children Mason and Penelope together.

A source told the site, "There's been buzz in their circle that Kourtney cheated and Reign might not be Scott's. He flipped when he heard it, and he's been off the rails ever since. Everyone's been saying, 'Poor Kourtney,' and she's been made to look like the innocent party. It's pretty harsh of her to make him take all the blame for a situation she may have had a hand in."

So far, neither Kourtney nor Scott have said anything about the cheating rumors.