Mel Gibson's Former Jumpoff Will Testify Against Him in Divorce Court!

Robyn Gibson just scored a major ally in her divorce case against husband Mel Gibson.

Diana Alouise had an affair in the late 1980s, but she says he was unaware Mel was married.

"We had a hot love affair based on sex, alcohol and partying, but it never would have happened if I had known the truth," she tells The Globe. "He told me he was married but that technically he wasn't with his wife anymore. I didn't really have any reason to believe otherwise."

She says they were jumping off for six months, but eventually dumped him after she learned he was married and had no plans to leave his wife. Now she's hell-bent on sticking it to Mel, by offering her testimony in divorce court!

"If she (Robyn) had to prove that he cheated on her so that she could get the settlement, then I would help her. I would stand up in court and do what I needed to do."

Diana, who once passed a polygraph test when she first came forward with allegations Gibson had cheated on his wife with her, adds, "I still wonder why Robyn stayed with him through it all, but one thing I'm certain of is that she should get half of his fortune. She deserves it."