In Touch has learned that Heidi Klum's new boyfriend, 28-year-old musician Tom Kaulitz, is married to businesswoman Ria Sommerfeld.

Divorce documents were filed in 2016, but the split has yet to be finalized. A rep for Tom tells In Touch the breakup was "mutual and amicable and all other statements are false," but a source claims it was ugly.

heidi klum

"He's a party boy. Cheating was also part of his lifestyle, and Ria couldn’t take it anymore," the source explains to In Touch.

"Tom made it clear he didn't want to give Ria any spousal support, but he did promise to help her finish her degree at UCLA," says the source. "Now he's claiming he's broke, but it’s just not true."

Heidi, 44, should proceed with caution, says the source: "Tom's immature. All he cares about is having fun, like a teenager."