OK, I had a suggestion from a friend of mine that the discussion is really something of an ultimatum. Either choose me and we work on this marriage or choose them and we get a divorce. His suggestion was that we have this conversation with the MC present to help keep us on track. I'm not very confident that my W will admit to what she doing if it's just the two of us, and I'm almost certain that she won't admit to it to someone else. So, I was thinking about confronting her on Thursday and having a MC appointment on Friday with of course the lawyer thrown in Thursday afternoon.
Or, maybe I'm still finding excuses to avoid the conversation.