Jim Carrey's Lawyer Says Mom's Lawsuit Is Another Sham

Jim Carrey's late girlfriend had a broken relationship with her mother and they were estranged for years ... according to Carrey's lawyer.

Marty Singer claims Cathriona White received a message from her mom a few days before her suicide that was so demoralizing ... Cat cut off all contact with her. He also says Cat was forced to leave home at the age of 15 because of the way her mom treated her.

Singer says the wrongful death suit filed by the mother, Brigid Sweetman, is headed down the "same dark path" as Cat's estranged husband's lawsuit ... which he refers to as a sham.

Carrey's lawyer says Sweetman is directing her grief and rage over the loss of her daughter at his client ... but it's just another attempt to capitalize on her death.