In Touch has exclusively learned that serial cheater Scott Disick "fell head over heels" for a new girl named Cassie Amato this summer — until he learned that the young model was also hooking up with 41-year-old actor Leonardo DiCaprio!

"Scott basically supported Cassie financially — he even paid for her to travel to the south of France and Mexico,” the friend says of Scott, who was smitten — until he found out about Leo.

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leonardo dicaprio

“She actually met Leo in Europe while on a trip that Scott was footing the bill for,” the friend tells In Touch, adding that Scott was humiliated when he learned the news.

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“Scott expected Cassie to be faithful,” says a friend.

For more on all your favorite celebrities, pick up the latest issue of In Touch, on newsstands now!