I should have separated when I was where you are, did not, and have paid the price. I believe we would have been back together now with my W committed and happier than she is now. It would have been the quickest and best path and is not giving up
Early in my sitch I read DR and Love Must Be Tough and I followed the advice in both and told my W that I wanted her to stay home and work on the M, but if she felt like S is what she needed to be happy then I wouldn't stand in her way. And she did leave just under 3 months after BD. It's been nearly a year since S and she is more set on D than ever before. I don't really see any hope for our M. That said, I do agree that in the end, S helped ME recover from BD much faster than if she had stayed home. I think we both would have been miserable for months and months had she stayed home. So S didn't save our M, but I think it did help both of us to move on.