Well until the true expert YAH chimes in I'll throw my two cents.

Sounds to me like for years you have been accepting "table scraps". She gives you a little to get you off her back, not really realizing that she is conditioning you to come back begging for more.

You have been accepting bad sex, with the notion than any is better than nothing. You have created, an expectation that bad (or partial) sex is good enough. This bad forced sex just made things worse and she cut you off. It's quite typical actually.

Of course the real issue here is the SA. You'll never make progress unless she learns to love herself, and then by extension you. Does she masturbate? Is she comfortable with her own body, does she ever bother to dress sexy for herself? Weight and self esteem issues?

I skimmed through your thread and read that once in counseling she completely shut down when confronted about her own issues. She avoids her issues to avoid unresolved pain. It's easier to paint you as the deviant than deal with her own issues.

Hell she'd rather buy you soft core porn than deal with her own trouble. I'm not a middle aged woman but I can tell the root cause is her not you.

Now that being said what can YOU do about it? Well step one would have been to no longer accept table scraps, but too late for that isn't it. She made that choice for you already.

You say you have tried to let her know how this makes you feel but clearly her insecurities are stronger than any concern she may have for you. Is this someone you'd like to be married to?!

You are entitled to your libido whether you choose to sacrifice it or not for her is up to you.

Which brings me to my next question, how the heck can you keep the sexual issue away from the rest of your M. I can see how and why your W does it, the SA. What about you? What keeps you in the M? Is all this worth sacrificin your sexual needs? I think valid questions which some have asked. Are you afraid of being alone? I wonder this since I am tempted to apply the "nice guy syndrome" label to you. Yet something is off. I don't know check out the book there's definitely a chapter about getting the sex you want, and not settling for scraps.

Another read that comes to mind is passionate marriage by schnarch. Almost pretty sure she won't go for it. Yet I'm reminded of the chapter where he convinced a woman to start masturbating and take control of her sex life. Once she felt in charge she was more comfortable sharing herself. I don't know some ideas.