I'm sure you've heard many similar stories. Mom is 83, and when she became unable to take care of her house any more we convinced her to move in next door to us. We did the actual moving across country for her, tough since she is a shopaholic and has three of everything ever manufactured.
It's gone downhill since then. One of my twenty something sons lives in her home and that is a great help to me since he regulates her pain meds and does her shopping. Another son's girlfriend cleans her and her husband's bedrooms and bathrooms. I cook for the eight adults in the two homes every night, and I'm a pretty good cook.
Mom complains about everyone and everything. She has an older sister who loves her, and every day she tells me how her sister is a mean drunk. That is an exaggeration, and every time she says it it grates my nerves. She's asked me to plant trees so our horrible neighbor won't spy on us. The neighbor is a sweet lady and too busy to care what we do, and I don't know why mom is so hateful. Mom has always been overweight, but due to bad health she's a lot thinner. Our best friends were visiting and she asked the overweight son if he planned to do something about it. Anyone who mentioned her weight in the past was automatically on her hate list. She threatens to kick out my son since he runs the AC in her house (we're in Florida) and says she has icicles hanging off her nose. He keeps it at 75.
Today is one son's birthday, and he suggested we grill steaks at home instead of going out so grandma can join in on the birthday dinner (she only likes to go out for lunch). I mentioned this to her and she made a sour face. I asked her what was wrong, and she said my son always ruins steak. He tried grilling them steak once when he was a teenager, years ago, and he overcooked them. She brings this up every time we have steak (maybe 2x a year). About a year ago I talked to her about trying to be kinder to people, and she turned it around and said I was bullying her and turned on the tears.
I feel bad about staying away from her, but whenever I go over to chat, she starts badmouthing someone. I'm sure she notices people avoid her, but I can't tell her why or she'll try to make herself the victim.