The Black Angel (L'ange noir) (1994)

Stephane, the wife of an older, prominent magistrate, coldbloodedly shoots a male visitor in her upscale home, then claims she was defending herself against a rapist. Victim turns out to be Wadek Aslanian, a gangster who's viewed as a modern-day Robin Hood. Paul, the lawyer hired by Stephane's husband, learns more than he really cares to know about his client, thanks to a series of anonymous letters. The notes provide a road map through the sordid areas of Stephane's past, allowing Paul to discover her history as an ex-prostitute, a porno movie performer -- and a frequent cohort of Aslanian. Naturally, Stephane's husband knows nothing about her past. Just as naturally , nothing that Paul discovers keeps him from falling in love with this mysterious woman.