I am so sorry that you have to go through this. But I agree that you have to get hold of the situation. This is YOUR life we are talking about here. I know this may offend some but, SHE IS NOT YOUR MOTHER, and there is a big difference between having your Mom live with you and taking care of her versus living with your MIL.
My MIL is 85 she lives in a senior apartment. very nice, but she is not content. she is always so negative and she can be mean sometimes. my hubby is always saying that the time will come that she cannot be alone and she will come to live with us. I say "over my dead body!!" It just won't happen!!! we have been married for 36 years and I will leave him before I put myself in that position.
He says that we had my Mom live with us and how is that fair that we put his mom in a nursing home? Then I just say to him that he will need to quit his job and stay home and take care of her.
You have every right to be resentful. you need to find a way to get your life back.
and the sooner you take hold of the situation the better for all of you. something like this will just eat you up inside and no one will be happy.
Keep us posted.
God Bless, Patty