CWMI, I think you are doing the right thing (which ought to scare the crap out of you). I think you should insist on your boundaries, even if it means the end of your marriage. I don't think you will be happy with your life otherwise, and I think you do have the capacity for happiness.

I hope I am proved wrong in thinking your marriage will end in divorce. I hope your husband steps up to the plate once you draw a firm line on what you will not accept. If not, his loss.

When you can see it coming, duck!