His Wife's Husband (1922)

Olympia Brewster marries John Brainerd to escape a life of drudgery and immediately realizes that he does not love her but only desires her physically. She leaves a suicide note and starts for her uncle's home, pausing only to see a woman shoot at her husband, apparently fatally. Some years later she marries George Packard, a successful lawyer who becomes mayor. A private secretary whom he hires turns out to be Brainerd, who blackmails Packard into rejecting a nomination for governor. But just as he is starting his speech, Olympia finds proof that Brainerd was already married when he married her.