Before taking any action, verify that the husband indeed has a mistress. Let's watch his behavior. If it's on a phone call, leaves the room, would often spend weekends supposedly "friends", has been delayed after work, not interested in the problems of the family - rather, he was interested in another woman. But to clarify everything accurately can only be a Frank conversation. 're gonna cheat and say that you called a strange girl and admitted in connection with her husband. Let's see how he will behave. If easy, I would say that this is someone's joke, he loves only you, then most likely rival you imagined. And if you start to make excuses to make trouble, shouting that he was framed, etc., so the reason for the experience really is.
After the conversation, do not take hasty decisions. If you want to keep the family together - we must act subtly. Pretend to believe my husband about the lack of a rival. But do think about why the faithful went "left." Most likely, you changed a lot after the wedding - relaxed, got fat, stopped to care for themselves. You don't have surprises and not interested in what my husband at the shower. It is this inattention to yourself and the lack of interest in the partner and pushed wife on the adventure. To return it to the family, you will have to change completely. Be a perfect woman - beautiful, slender, sexy, well-groomed, popular, caring and passionate. After seeing your transformation, the husband must return to his family.
It is not necessary to call a rival and scandal. To anything good it will not. She will tell her husband about it. He gets mad, more at myself for not being able to cover their campaigns. And that anger will push him to serious decisions. Or he can stay in the family, deciding that the best wife no one. Or will go to another, realizing that to stay with his wife no longer can. If you are not confident in their abilities, do not let the opponent to understand that I know about it. When you converted, conversation with her is not required, the husband himself will break this relationship.