I have thought a lot about this and I am having a hard time putting it into words. When I first ended the A, I believe I was ready to make my M work, but that is easy to say now and maybe I would have needed space no matter what.
I understand how it is hard to be fully committed to someone that you cannot trust, that has just betrayed you in the worst possible way. Now, switch that around and ask yourself how easy it is for the WAS, who left because they felt they were out of options, and think about how hard it is for them to give up what they now believe is the only person who can make them happy, go back to a M that they felt was sucking the life out of them and commit 100% to a person who won't commit 100% to them because of what 'they' did. It isn't easy.
I personally do not believe you can save your M until you get to the point where you are both fully committed. You may make a little progress if only one is, or if one is half in/half out, but you will not save it.
I believe you have to be willing to take that risk. If you are there anyway, giving it half a chance, you will still be hurt if something goes wrong. If you are making the decision to stay, you need to be all in.
When H and I were in MC, I originally wanted to be there. However, I then found out that he went to a lawyer to 'find out what his rights were' and that spoke volumes to me. I spent the next 18-24 months going to counseling but I no longer cared. At that point, I started regular contact with OM again and it lasted a long time.
If you are going to try to R, you have to be willing to commit to the M and be willing to take the risk of being hurt again. Also, leaving it up to the WAS to prove that she is willing to do what it takes, not leave you again, not cheat, etc. goes back to saying that what they did is so much worse than what you did. They are also taking a risk that they will be back in the same M that they couldn't handle in the first place. It can be a vicious circle!
M 46 H 44 D 12 S 8 M 9 T 11 BD 2/15/13 "Makes sense to stay together" 5/12/13 Agree we are 'healing' 7/13 Definitely Piecing 9/13