I think ROOT was trying to say to do it calmly. I agree that you catch more flies with honey than vinegar. (It worked for me, but perhaps because I was honey, and OW was vinegar.)
Saffie has a good point, too. Every sitch is different. What works for some doesn't work for others because of that. And only you know what your boundaries are and what you'll willing to put up with.
Lurch, you know your sitch and your W better than we do so think it through. Telling her you know would give you an opportunity to talk about your problems. If she thinks you don't know, and you never talk about it, you won't gain anything. Back to what Choc said first, if your goal is to save your M, then you should confront and expose ... calmly.
