Madame X (movie, 1966)

A woman married to a wealthy socialite, is compromised by the accidental death of a man who had been romantically pursuing her, and is forced by her mother-in-law to assume a new identity to save the reputation of her husband and infant son. She wanders the world, trying to forget her heartbreak with the aid of alcohol and unsavory men, eventually returning to the city of her downfall, where she murders a blackmailer who threatens to expose her past. Amazingly, she is represented at her murder trial by her now adult son, who is a public defender. Hoping to continue to protect her son, she refuses to give her real name and is known to the court as the defendant, "Madame X."