You should have not left him. This attitude serves as a breather and very relieving for the men. Go back as soon as possible. Try to talk to that woman in a sensible way. Being a woman, she may understand your feeling better (I’m sure you must have had hard time convinceing your husbund). You may speak to his friends and concern relatives (although doing this may invite some fights between two of you) and expose him in such a way that he feels ashamed of what he has done.