Welcome to a safe place in the world! I understand your feelings of resentment with total sympathy. When you didn't choose to do something and you're saddled with it and it makes your life harder in ways you never imagined, resentment is sure to follow.
I just recently put my mother into a nursing facility after taking care of her for over 8 years. I put my life on hold literally since I was 19yrs old for her -and I thought that she would surely see that I couldn't do this for all of my life. Unfortunately that is what she wanted, her needs and wants put ahead of everyone else, and kept in her comfort zone regardless of the time frame. She told me how many times that as her daughter that's what I'm there for. As if I had no choice of what happens to my own life. I had to display tough love and demand that she go. It's not like I suddenly stop doing anything at all for her. I have to visit, and take her necessary monthly things. Anyway, the point I'm trying to make is your life is important, your needs are important and lo and behold your hubby's FIRST priority is to YOU his wife, the one he vowed to love and cherish.
I would think that a serious family meeting must be held. Sometimes you have to be assertive and be your own lawyer. Don't be emotional and vent and carry on, just speak your mind, lay your problems on the table in a way that perhaps a man can tackle in his task orientated way. Your family life and marriage falling apart is not acceptable. Show him that its for both of you and the family that you need changes, real changes. No-one can always get their own way, (unless you're Paris Hilton or something) and that applies to MIL as well. A more amicable agreement needs to be worked out, one that you can work with, not just survive.
Apologies if any of this was a bit much, when I start talking I sometimes get carried away!
Stay strong, and look after yourself