I know I'm in the minority here but I think that her marriage can be saved if she wants to go that route. Lots of people on this site save their marriages while their spouse is out galivanting around with other people. It isn't right but it's done all the time. This lady instinctively knows that if she makes an ultimatum between her and the OW, he will choose the OW and the life of (relative) freedom, and be out the door.
So the question is not whether she should continue to ML to her husband (imo, this is a good thing, especially if that was one of his reasons for leaving) but whether he is WORTHY of having her as a wife in the first place.
Don't underestimate yourself, nj, in an effort to 'win' over the OW. Do you really WANT this man back? Is he a good husband and is he worth the effort?
Furthermore, are you willing to make the permanent changes that would be necessary for his happiness? Would he do the same for you?
If the answers to these last questions are yes, then fight with everything you have. Protect yourself financially and against disease, of course, but continue on the path that you have been on.
From what you have written it doesn't sound like he is much of a prize, but then again we all have a tendency to downplay our own role while emphasizing theirs.
Try to look at things objectively and assess whether he is actually worth keeping.
