Sorry you are facing this. It hurts like heck. It is pretty typical. They just have to have a D. They either can't explain why, know why but won't say, or have someone else on the side. I'd be willing to bet there is many things my W kept from her C or she told her C everything which is why she didn't want me to see her C.
It sounds like you did a good job. But she seems adamant to get out. This is going to be a tough time for you, I'll be honest. You have to detach from it as much as you can and try to be a friend to W when she needs it. Regarding M/R - all you can do at this point is let her know you stand for your M and if she needs to talk - you are open to talking with her. At this point, you should not initiate any R or M talks. Let her intiate any talks about the R/M. In the mean time, GAL, do 180s and try to keep the PMA up as much as you can.
As you point out, not giving them anything to fight seems to back them off a bit. It takes two to fight and argue, as soon as you learn to bend in the breeze - you can free yourself from this.
Pray the serenity prayer as much as you can. Remind yourself that you cannot control anything about your W. All you can control is yourself. Treat any time you have to work on yourself as a gift. And no matter what, do not allow the spew you may get through this process to damage the good memories of the one you fell in love with.
Pray my friend and know that you have others here that care about you and will be praying for you too.