Everyone has told you what to do, and you argue that it is impossible. Well, maybe it is. You won't know unless you try.
1. Tell her "Enough! You love OM. Go be with OM. I won't live in a sexless marriage. Starting today, I am looking for a new wife. I am done with you. Move out."
2. Live up to your word. Make her leave. Let her chase OM. I missed hearing the part about how he is going to divorce his wife and marry and support your wife. Or maybe he is going to support them both. Good for him!
3. Ignore her calls if she calls. If she doesn't call, you haven't lost anything that you had anyway.
4. If she cries and begs and pleads with you, insist on a Retrouvaille weekend. It is not therapy. No one tells you who is right and who is wrong, or what to do. You haven't even looked into it. You reject it out of hand. If you want to rekindle romance, you go to Retrouvaille. If you want to bask in self-pity.........keep doing what you are doing. It is working great!