Then tell her you know what is going on......but do not tell her how you know or what you know. Tell her that you will not be in an open M. Leave it at that and do not get into a talk. Let her stew about what you know in detail, how you know, etc. do not start professing how much you love her or what she will have to do to save the M. Just state you know she's in an A and you won't be in a M with three people.
Then remove her things from the master bedroom and stop sleeping with her!! Set it all outside the bedroom doorway and let her have the job of figuring out where to put it and where to sleep.
Your biggest problem is wanting to justify your actions with your W and her friends. That is why you want her to know you know. You care too much what they think about you. That is why you want them to know why you are doing what you do. They are assisting her by encouraging her. When you live your life by wanting your enemies to approve of you.....you become a slave. Free yourself of this type of thinking.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
