LEONARDO diCAPRIO  might look like a man in lust with hottie ERIN HEATHERTON, but insiders say he’s still hung up on his ex, supermodel BAR REFAELI.

“Leo is using Erin,” said a close pal of the 37-year-old “Titanic” star.

“She’s nice and all, but she’ll never win his heart. He hasn’t gotten over Bar, and in many ways he never will. She’ll al­ways be the one who got away.”

DiCaprio and Victoria’s Secret beauty Erin, 23, cozied up in Hawaii recently, and while she’s reportedly madly in love with him, DiCaprio’s pals say she’s headed for heartache.

“Erin’s playing the perfect low-maintenance girlfriend, but Leo’s going to get bored with that fast,” predicted another source. “He loved Bar’s feisti­ness and her ability to stand up to him. She was the only girl who was able to drag him home to play dutiful boyfriend. He wanted to marry her and even c o n s i d e r e d converting to Judaism for her.”

DiCaprio and Israeli-born Bar be­gan dating in early 2006 following his five-and-a-half-year romance with Brazilian supermodel Gisele Bundchen. After a series of breakups and makeups, Bar finally called it quits in May 2011.

“Leo didn’t quite realize it was for good because they’d split so many times,” said his pal. “And when he heard she’d started seeing other men, he reacted by go­ing on a womanizing rampage.”

That included wooing “Gossip Girl” beauty Blake Lively before hooking up with Erin. But pals insist the “Inception” star is still stuck on Bar.

“Unfortunately for Leo, Bar wouldn’t touch him again with a 10-foot pole,” said the source. “She’s moved on after making the mistake of thinking she could change him. But Leo will always have his ego and his roving eye.

“Don’t feel sorry for him, though. He brought it on him­self. The one who deserves sympathy is Erin. She’s a really sweet and genuine girl, but she’s just another notch on his bedpost.”