Some people would disagree with this, but I wouldn't tell him either. Why hurt your husband when you don't need to. I still do believe in monogamy. I would start going to therapy first. I seem to think that you would need to heal from the affair before you can try and make your marriage work. Then again you need to figure out why you had the affair. Did you end the affair because of your husband? Or did the guy you had the affair with, end it with you? You also might need to come clean about the whole entire thing before you can move on.