Nicolas Cage is far from Father of the Year in the eyes of his ex, as Christina Fulton is now suing him for fueling their son’s violent tendencies … which she believes led to him attacking her.

Christina’s filed the suit against Nic and their son Weston Cage over Weston’s brutal alleged beating of his mother in L.A. last April. As you might expect, she’s suing Weston for assault, battery, negligence and infliction of emotional distress — but the legal twist here is she also thinks Nic’s negligence played a big role in the abusive incident.

In the docs, obtained by TMZ, she says Nic was well aware of Weston’s history of mental and psychological disorders … but instead of addressing it, the actor enabled it. Christina claims Nic gave Weston financial support, bailed him out of jail multiple times, but never pushed him into getting any professional help.

As we reported, Weston was arrested and charged for attacking his mother in a parking lot, elevator and lobby of his apartment building. The aftermath pics of Christina were horrifying … and according to the suit, she suffered a concussion, multiple contusions, neck and throat injuries, and a disfiguring eye injury.

Christina says the attack has derailed her acting career and business ventures. She’s seeking damages from Nic and her son.

Weston has pled not guilty to assault with a deadly weapon, but has yet to stand trial.