Hello cat: I'm sorry you are having to deal with this difficult family situation. Thanks for sharing it with us here on PC. I'm afraid there's probably not a lot I can offer in the way of advice. But perhaps this article from the PsychCentral archives on how to deal with difficult family members can be of some help:

https://psychcentral.com/blog/archiv...amily-members/

One thing I particularly liked in this article is the quote from Don Miguel Ruiz (The Four Agreements):

"Nothing other people do is because of you. It is because of themselves. All people live in their own dream, in their own mind; they are in a completely different world from the one we live in."

Perhaps if one can think about it in those terms getting along with difficult people, whoever they are, can be a bit easier. I wish you well...