She always thinks she is the best and smartest. She has not been nice. She is defiantly repetitive but thinks everybody else is dumb. She has said that she repeats because we are too stupid to understand. I know this is probably the dementia. I kind of blame her for her husband's death. He broke his hip. I think she pushed him but no proof. She has called us nasty names and is hard to deal with.
There is no point in telling your MIL about her behavior if she's not going to acknowledge it or recall you mentioning it. If you go to visit her once a week and she gets nasty, just let her know you're leaving BECAUSE she's acting nasty. That ought to get the message across to her loud & clear.
If she's living in Assisted Living and 'needs help', pay extra to get her the help she needs, plain & simple. If she needs you to bring her supplies or something on that order, bring them along with you when you visit or have them sent to her via Amazon.
Good luck!
I wouldn't be in contact with someone who made all contacts with him or her unpleasant myself, and it would matter little to me that we shared blood or genetic markers.
Yes, it probably is the dementia, unless she's always been like that, but you don't have to accept that as an excuse for her behavior.