Diary of a Mad Housewife (1970)

Tina Balser is a bored New York housewife-mother married to Jonathan, a pompous, social-climbing lawyer who ridicules her in front of their children, criticizing everything she does or wears. She begins an affair with George Prager, a dashing, successful and blatantly sadistic writer.

Finally after George has tormented Tina in much the same manner Jonathan has, and has been unfaithful to boot, she goes back to her husband and begins group therapy.