Incredible revelation as Dina Lohan reveals on tape that daughter  Lindsay was secretly dating the late Heath Ledger when he died of a drug OD!

RadarOnline.com in an exclusive bombshell leaks an audio taped phone conversation between Dina and Michael Lohan in which Dina says that Ledger and Lindsay had been dating at the time of his tragic death in January 2008.

"And she was dating Heath when he died," Dina says on tape to estranged hubby Michael. "I don't know if you know that, but I know cause I would drop her off and they were friends very, very close, ok?"

"Because when she's drunk or takes an Adderall with it she will do something like Heath Ledger did in a second without thinking."

Dina says Heath's sudden death was was a terrible shock to Lindsay. "That f-f----d her up."

To hear the shocking tape CLICK HERE