Justin Bieber 'cheated' on ex-Selena Gomez with Miley Cyrus

Justin Bieber has allegedly cheated on his former girlfriend Selena Gomez with Miley Cyrus.

Gomez revealed during her two-week stint in rehab that she broke up with the 19-year-old singer after she discovered he had cheated on her with a close friend.

According to a source, Gomez claimed to be struggling with Bieber's infidelity and his obsession with hooking up with other women, Us magazine reported.

The source added that dealing with the stories about Bieber's hook-ups was bad enough, but hearing that he was involved with one of her closest friends was the ultimate betrayal for her.