stitch, the way it sounds it seems she has entered the "chase of happiness" phase. She has detached from you and she probably thinks happiness is not where you are. Back off, read DR, read "his needs, her needs', focus on you.
Could there be another man in the picture? The underwear thing sounds funny... Stay strong. This is no easy battle and there are no shortcuts. I am all for "tough love". Read threads on here, try to find the threads with advice to newcomers. Your sitch is very common. You are not alone. K