I do think you should expose their affair to the OM's wife. She has a right to know.
Oh please. Tell OM's wife. Wouldn't you want someone to tell you if you were completely in the dark? I was made a fool of for months until OW's H told. I still can't thank him enough.
Does your W have any family she can stay with until the D would be final? I think your rule of not dating while under the same roof is solid. She is obviously dating. You cannot work on anything unless your W is completely committed to fixing things with you. I know this is a 'save your marriage' website, but in the process, we have to save ourselves, huh?
