Hi Mrs K, welcome.
I know that feeling. It's etched on my memory. I'm 62yo and up until 54yo my mother had left a train wreck in my life and my sisters life. My mother ruined my first wedding in 1985. She sued her brother instead of rining him to sort out family mess etc etc.
I only found the real issue when someone told me to google
waif queen witch hermit
But that doesn't mean your mum has the same issues.
We tolerated comments about the partner she wanted us to have, that we were never good enough, the manipulation, the negativity, all got too much. But the dividing of my sister and I was nearly the end. My sister and I pledged to never be divided again and it was only time when my mother rang with yet another false medical diagnosis , an argument, then straight away ringing my sister to get support against me, This happened all out lives. But when she threatened to ruin my next marriage in 2011 the line was drawn. I even got and AVO out to ensure she didn't turn up as threatened, in the park, to ruin everything.
So, to answer your question- drift away. Don't answer her calls if you don't want to (she might hound others then), if she starts a rant calmly walk out and drive off. in short- draw your own line of tolerance and support. That way you are giving yourself every opportunity to tolerate her on your terms, not hers.
This might seem a method to disrespect her. Not so. It is a method to tolerate her with a likely ongoing medical condition of which you are not privy to what it is, because she wont get help.
We tend to not place such judgements on others as it seems too harsh but they themselves cause it. Be firm, direct, calm and fair. Your health is number one. You might find if you had a diagnosis that your own problems stem from this erratic behavior.
Topic: does stubbornness have a place?- beyondblue
Topic: is there any room for stubbornness?- beyondblue
Good luck. You can reply on those threads or reply here if you choose.