"Indeed, I have done a lot of thinking about how we could come up with a compromise, and we did that for some years, where I would experience release but she was not sexually involved at all. But that only works for me if I can keep thinking of it as just one of many different things we're doing. But after a long time, her complete lack of participation made me feel very "left out" and more of the mindset that I have more and more good sex to make up for."
Very sad for both of you. But you do realize, of course, that this was almost certainly like another extended period of molestation and sexual abuse in terms of her feelings and experience of what was going on. I am in no way suggesting that you coerced her. I am merely stating how she almost certainly felt -- silent, passive, unable to stop the sexual use of her body by someone she loved. Until the two of you confront this aspect of your R, now that she has found the strength to resist what may well have felt like assaults to her (even if she rationally knows they were not), I doubt anything will work. And, neither of you may be willing to confront and deal with this until your M truly is on the line. So, back to PM.