If your W is going through MLC, you have to realize that it is not about you. It is about her and the pain she is feeling. She is lost and searching for a solution. Because you are the closest to her, you will get the blame for all her problems.
The OM is a band aid to her problems. She feels infatuated with him and thinks that infatuation is happiness. At the same time, she feels guilt over what she is doing to you.
You are not dealing with a person that is rational right now. You are dealing with a person that is running completely on emotion.
Don't confront your W. It is the worst thing you can do. You will push her further away and right to OM. There is nothing you can do right now to talk her out of it. She will reject all who try to stop her. That includes you, her family, and friends. She will surround herself with people that do support her and validate her in her actions. My W barely talks to her family. Hasn't spoken to her father in almost 3 years and has almost entirely new friends since the bomb.
The important thing to remember is that the more you push her, the more she will pull away. I pushed really hard and my W ran really fast.
Hang in there. This will be the hardest thing you have ever done but you will get through this. The pain will subside. Succeed or fail you will be a better man for trying.
M35 W37 S9 D6 M12 yrs Know 15 yrs Bomb 1/28/07 My Sitch Failure is the opportunity to start again more intelligently - Henry Ford