It's weird, but I seem to be seeing this more and more often when a couple reaches the mid to upper 30's. The husband is slowing down, his metabolism is crashing and hair is thinning. The wife hits her stride (called "the dirty 30's") and doesn't find her husband as attractive anymore.

You both need counseling, probably as a couple and individually. If she's not interested in a counselor as you say then you've reached an impasse. A relationship is about compromise, deal-making. When one member of the relationship won't compromise then there really isn't much of a relationship ... more of a dictatorship.

This is going to sound harsh, but it's the best I can do with this one side of the story.

1. Couples counseling is probably a must for you guys to continue.
2. If she's done with the relationship, she's done. Don't be friends afterward. That's just her torturing you and you don't need those childish games.
3. She's not worth harming yourself over. Even if this ends poorly, you can still go on and have a very happy and fulfilling life without her. In many ways, she's holding you back now.