Help! I think my mother-in-law is ruining my relationship?

My husband and I have been together for more than ten years. I have never really liked his parents or been comfortable with them at all. They are very socially inept and dysfunctional. Early on, I tried really hard, but never got much of a response back. I can deal with my FIL because what you see is what you get, but my MIL pretends to be the victim in their relationship and it's really annoying. Also, she's stabbed me in the back more than once. My husband deals with them by not dealing with them. He has already told me that he cannot be in the middle anymore. The problem is that I'm pregnant with our first child. I know that it's important for my child to have a relationship with his grandparents, but I don't really want a relationship with them. This is already causing some grief and arguments in my marriage. I don't know how to fix it. All I know is that my MIL has never been willing to change and is really manipulative. I can't see myself going along with whatever they want the way my husband does. This is the only thing we fight about. Is this problem going to ruin my relationship with my husband? How can I facilitate a relationship between my son and a person I don't respect?