What would you do?

This August My wife and I will celebrate 35 yrs together. Since day 1 her dad has been an asshole. Thats as nice as I can say it. Her mom is the sweetest thing you could ever meet and has put up with so much abuse both verbally and mentally since I met her. Many times she says I dont know why I put up with him but at her age its a little late to change. My wife spent 3 years in counseling trying to resolve issues from her childhood around him. The first 10 years we were married I just refused to speak to him. He is 88 and mother inlaw is 84. He cant do much because he is to heavy. However he wants no help from anyone and then my mother inlaw has to help him do things and that puts her at risk of getting hurt. This summer he fell from a ladder because he couldnt wait for someone to help. When it snows she has to go out and help clean the driveway and its on a pretty good slope. Shes had 2 hip replacements a knee replacement and shoulder surgery in the last 10 years. When we get a big snow like today thats over 4-5 inches she always asks me to come clean their driveway. Well in the past that meant loading the tractor up on my trailer and driving over. Well this summer I told her I could just put my spare tractor and snowblower in their garage for the winter that way it would be easier. They only have 1 car since he cant drive so theirs plenty of room. So today we get almost 10 inches of snow. I go up get the tractor out and clean the driveway, When I pull the blower back into the garage he comes out and asks me when Im getting it out. I said when its done snowing. He looks at me and says I want it out. So I tell him thats not a problem, from now on he can clean his own driveway. Then I go in and tell my mother inlaw Ill be up this weekend to get the tractor out. She apologizes for him and I told her Ill do anything for her all she has to do is call but for him I will never help with anything. As I was leaving I had to walk by him outside, I told him he was a bastard! I didnt say any more although I wanted to but I decided not to go there. (once I cross that thresh hold it would have been a no return area!) When I came home I told the wife that I would never help him again. Its a tough situation because I dont want my mother inlaw falling or getting hurt doing stuff. The wife hasnt said another word about it. Not sure where this will go from here but Im done with him!
Thanks for letting me vent.
Rod