RYAN O’NEAL’s troubled son GRIFFIN has taken aim at his father in a new U.S. tabloid expose, in which he accuses the actor of cheating on his late companion, FARRAH FAWCETT, and breaking her arm in a rage.

Griffin, who was banned from Fawcett’s September (09) funeral by his estranged father, insists O’Neal only stood by his on/off girlfriend as she battled cancer to make sure she didn’t leave him out of her will.

The 44 year old tells the Globe, “I believe my dad’s only goal was to make sure he’d be in Farrah’s will.

“My father cheated and lied and was abusive to Farrah. She did not deserve that… He was an infidel.”

And Griffin has come forward with claims his “violent” dad, who allegedly knocked out his son’s two from teeth in a fight, once broke Fawcett’s arm in a 1983 row.

Griffin adds, “My dad went into a rant. Farrah came flying at him to defend herself, he blocked her and, in the process, broke her arm.

“They spun the truth to protect Ryan (but) I was there, I saw it happen.”

It’s not the first time Griffin has gone public with outrageous claims against his father: Earlier this year (09), he alleged the actor and Fawcett’s close friend Alana Stewart had become romantically involved during the last months of the actress’ life.

He said, “They were sharing a room together.”

Both Stewart and O’Neal dismissed his accusations.