Madame X (1966 movie)

Madame X is a movie from 1966 starring Lana Turner, Constance Bennett, John Forsythe, Ricardo Montalbán, Burgess Meredith, and Keir Dullea. It was directed by David Lowell Rich and produced by Ross Hunter.
Plot.
Holly Parker marries a rich and ambitious politician named Clayton Anderson (Forsythe). He is often travelling. Holly steps out now and then with Phil (Montalbán). She breaks the relationship off, but Phil refuses to be dismissed. He dies while arguing with her.
Holly's mother-in-law (Bennett) realizes the scandal will destroy her son's political goals. She tells Holly to disappear forever by staging a fake drowning. She does so, and flees to Europe.
The years pass. Holly drinks heavily and pals around with Dan (Meredith). They return to America. Holly discovers Dan plans to blackmail her husband. She kills him. She refuses to reveal her identity to the police, and signs a confession with the letter "X".
The court assigns her an attorney who happens to be her son Clayton Jr. (Dullea). The trial is nerve wracking for Holly. Weary and ill, she dies in jail without revealing that she is her attorney's mother.