Bottom line, though, I was slowly losing my wife and my marriage by keeping quiet and trying to go along, hoping I'd find a way to make her happy. What made her happy was finding herself married to a man she could respect, which was impossible until I stood up for what I believe and want.
This is soooo spot on.
LaSombra--you're right. Sex isn't everything in a marriage but it is a (big) part of it. You should tell her that.
There is some disconnect going on if she's saying she doesn't want sex but also note it's definitely tied into her "not feeling the same" about you. Women tie a lot of their emotions into sex. If she feels the emotional part of your M waning, she won't be as sexually attracted to you.