The MIL bought a house across the street and has no concept of boundaries. How can we get control before it's too late?

My husband and I have been married for nearly 18 years, so the MIL's personality is not new. She is 80 and my husband is an only child. She is well-off, extremely controlling, and manipulative. She can be very hateful toward her son. She is selling her million-dollar home across town and bought a smaller home across the street from us. Two and a half years ago she came to us and offered a downpayment for our new home, which was a huge mistake as I think it was carefully planned. She is on the title too. It is a beautiful home and we like it, but from the get-go my husband had foresight and said absolutely not. She hounded us relentlessly until we caved, which we should have never done because we were fine living within our means in our previous "dump" that she hated. She picked on us for 12 years for buying it; probably because we did it all on our own. We were happier there.

She had a stroke 6 years back and rehabilitated beautifully, but is a fall risk. She still drives. She is completely independent in decision making and handling her finances etc. She purchased the little house by us about 8 months ago and has put 125K more into it and it is finally done. We were very up front with her at the beginning that we would not move her household and that she would have to hire people for that. She has a 5000 sq ft house that is full. She agreed. Since then, my husband has been down there several times filling his truck up and bringing loads of stuff to her home out here (40 miles round trip). She says he does nothing to help her. He does a lot for her, but does manage to be firm about what he will and won't do, but that makes him a "bastardo." I will run over and do whatever she wants, which is a lot. We pay for her cell phone, take her trash to our house (she won't pay for trash service), do all the little chores, fix meals, take her shopping, and on and on. My kids do things for her too when they have time, but they also work and are taking college courses as high schoolers and have almost no time to spare.

The problem boils down to every time we say no, it turns into a manipulation-fest of "you kids never do anything for me" "I'm all alone and have to do everything on my own" "you kids just thumb your nose at me" "I have ruined my health doing everything on my own when the only reason I moved out here is to help you." She lets us know we don't deserve any inheritance, which with the resentment we feel, she is probably right.

She never calls us without a demand and it's always and emergency and can't wait. If we say no or we will do it later, we have to hear about it for weeks to months afterward that we treat her badly. She asks my kids to come over and then tells them how pissed she is at us for abandoning and ignoring her. Two weeks ago she called my husband on his cell to come right over and take some stuff out of her car that she 'managed all by herself to put in the car even though she could barely do it and almost fell down blah blah.' He was at a friend's house (which is rare) and he told her he would come over when he got home, which he did, immediately. Over and over we have to hear about how his friends are more important than her (which is nothing new) and he was "too busy" to help her. She will work herself into a frenzy over stuff like this. She keeps written logs of when we say no and keeps track of when we have friends at our house. She is the only thing that makes our marriage difficult because of the strain of the demands and the never ever being able to please her. We keep quiet and don't fight her.

She is a smart cookie, like a lawyer. If I try to defend myself, it is only minutes before I am believing that I am such an a-hole. I want to run away and my husband is about to walk away from her BUT she is now our neighbor, and she's 80, and she does need our help. I feel so powerless and I am so fatigued already. She will not take no for an answer. I feel owned. I am now going to do a garage sale for her all next weekend to sell just a little bit of crap (donating is out of the question), but it has to be done right now and can't wait, even though I know she is going to need 10 garage sales before this is over. She does say thank you, but grabs it right back with complaints and criticism. One of the kids baked her some peanut butter cookies last weekend and she said they were good, but "it would have been better with nuts instead of creamy peanut butter."

I have read a lot of stories on this website and know that I do not nearly have the problems others do. I also understand that there is a longstanding family dynamic of a not-so-good relationship with her to begin with. I am already overwhelmed and can't keep up with my own chores and it is going to get much much worse. I also have my own elderly mother who needs me, but the MIL is very jealous of that too. I admit that the hope of inheritance is my carrot. I really am an a-hole.