Your best bet is to just go with the divorce... do you really want to fight it? Trying to talk her out of divorce and out of the relationship with OM is a complete waste of time. The more you are against this, the more she will want it. At this point she probably only wants the divorce... not because she wants it, but because you don't want it. You need to let go.
What? I thought this was Divorcebusting.com? Have I been on the wrong site this whole time?
Ok, I have to address this one...
My W suffers from a disorder that is based on the fear of abandonment. Abandonment does not have to mean simply leaving, which I did threaten. Abandonment to someone with this illness can mean something as simple as being gone at work too long, or using a tone of voice that reminds her of a parent who emotionally had checked out during her childhood. It also causes the person to see things in a state of black and white, vs. shades of grey. This means if a friend or mate does one little thing to hurt her, she feels abandoned and will see the R or person as all bad. Normal R conflicts are so threatening to her that she becomes offensive in her attempt to be defensive from oncoming attack that was never intended. This is an illness she has suffered long before I entered the picture, and one that has been the root of nearly all of her demons, which for the most part, led her to the OM. She is very intelligent and talented and normally thought this guy was a sleaze ball. After suffering a series of serious seizures and being stuck in bed on high dosages of three different meds for 5 weeks, she went ballistic- burning the candle at both ends (and making some new ones), and being both very fearful and very angry that these seizures were happening. Couple that with an emotional illness and other health issues, drinking regularly while on these meds, and fearing she will never be normal again, and trust me, my W doesn't know how angry she has become, and she is surrounded by a big dysfunctional group of enablers. The OM is preying not just on my W, but on a good hearted woman who has an emotional illness, and has just suffered life-altering seizures and medications that further change a person's personality. I am the only one who fully comprehends the scope of her issues as well as the dynamics of how she got them in the first place. Waste of time? My W is my best friend, and I'll tell you what, if it were me in her shoes, I would hope she wouldn't let go of me and feed me to the sharks at the weakest point in my life, even of that friend was the S I was leaving.