How do I keep my sanity or my marriage intact if my FIL moves in?

In the beginning of our marriage I knew that my MIL was a handful and said things to undercut. She didn’t even stand up at our wedding while we cut the cake or toasted (which she denied). I didn’t know what I was getting myself into until two months before the wedding. We lived in another city and decided to move closer to his family because they were getting old (6 years ago). A few years went by and I continued to try and have a relationship with her but she always had a way of saying the wrong things. So, sometimes when my husband wanted to go to dinner with them I would decline. He would get very angry at me each and every time but I didn’t want to put myself in a situation where I always felt attacked.

Fast forward to my MIL’s death in January 2013 that broke my husband with guilt (for not donating her a kidney) as well as my guilt for always trying to stay away.

His dad, my FIL, is 80 years old. I planned, organized, and paid for an 80th surprise birthday celebration that cost us thousands of dollars. I also make it a point (when my husband works out or hangs out with his friends) to call his dad and hang out with him. He’s a really cool old father in law!! He repeats himself a lot, he talks just to talk, but he is pleasant to be around.
For the last year my husband and I have talked about getting a one story house so his dad can spend the night (we have a two story with all bedrooms upstairs). So if he comes over to watch a football game he has to leave before dark (can’t drive at night). His dad has his own home that he shared with his wife. In recent months we’ve put our house on the market and my husband and his dad start talking about all of us living together under one roof. I have said time and time again that I would love to do that IF we could find a house with separate living quarters (apt). There is no way I can live, pick up after, cook for, take care of TWO MEN!! I just can’t mentally do it.

This morning I was telling my husband I needed to pay the credit card so I could buy our tickets to go see his sister graduate from college and he snapped at me. He said, “I’m not going to the graduation because I’m taking my dad out of town for surgery”. I started asking him questions about what kind of surgery, when, etc and he said, “I know you don’t like my dad so I’m not going to let you keep me away from my dad like you did my mom”. First of all, I never kept him away from his family if anything I would encourage that instead of him hanging out with his friends. I don’t have to be with him every time he hangs out with his parents or do I?

He never spends alone time with me. If we go to dinner his dad goes 100% of the time and invites him everywhere we go. Which is ok but when he goes and hangs out with just his friends he never invites his dad. I know his dad moving in with us will destroy our marriage. He’s already guilting me when I expressed my desire for us to either get an inlaw suite (detached) or just by a house in the same neighborhood as his dad. Can anyone give insight as to what I do? We maybe see my parents once a year and even when my parents call to tell him happy birthday he doesn’t call them back. It’s like my life outside of his means nothing!!