Maybe you need some perspective. If my W was still in the house, I'd hug her and love her and be the happiest guy ever - and never mention OM. Here's the thing - your W has an obvious connection of some sort. Talking about it isn't going to handle it and cutting her off isn't going to handle it, unless it's your boundary.
From what I'm reading, you aren't presenting an attractive picture at all. I see sadness, depression, anger, angst, grumpiness, etc. Have you considered counseling or medication if necessary? It seems to me the reason W stays in contact with OM is because you aren't anyone she'd want to share with or spend time with!
It's hard work - I know how it is to feel crushed, alone, etc. But I have focused on working out, kids, friends, finding things to do. I started keeping some distance with W (easier for me since she is living separately), and she has started to show interest.
If you're not going to file divorce, your only other option (besides hating limbo) is to love your wife - so go for it! I had to make that hard choice not long ago...
