Sweet Vengeance (1970)

Gambler Mark Stevens is brutally beaten and murdered by "The Bear" under orders from Big Mike, a New York City gambling syndicate boss to whom Mark owes a sum of money. Betty, a woman with whom Mark has been having an affair while his wife, Helen, is away on a business trip, witnesses the killing and decides to avenge Mark's death. (Betty is a friend of Helen's who has recently arrived in New York and is living with Mark and Helen while looking for a job.) Betty learns how to use the blackjack and razor from a homosexual photographer, and she repays him by allowing him to paint her body in psychedelic colors. Betty then infiltrates Big Mike's syndicate through his procurer, a lesbian, and receives from her a date with the syndicate boss. Betty seduces Big Mike, then beats him to death with a blackjack and castrates him with a razor. Fleeing his apartment, she stumbles into The Bear, slays him, and, pursued by one of Mike's henchmen, joins Helen, waiting outside in her auto. A wild chase takes place up New York's West Side Highway, culminating on the George Washington Bridge. There the women realize they are doomed, and, turning their car around, they crash head on into their pursuer's oncoming car.