I'm sorry for your continued suffering in this area, and I hope you find your way to a peaceful resolution. Your suffering needs to be addressed.
Yes. You seem to believe that if you change your relationship by having your reasonable expectations met your suffering will end. You are frustrated and passionate about this.
Yet this approach isn't getting you anywhere, is it? What you expect, as reasonable at your expectations are to you, seem beyond what your mother can give you.
Perhaps she cannot give these things to anyone. I think of the example you give regarding her neighbor. This is her way of living, perceiving and responding.
The only way to win this endless battle is to not play the game. It is a game. Think about it. You know the rules. You know the triggers. You know whose turn it is to play. It's almost all on automatic now.
How can you disengage? That doesn't mean abandoning her. It means visiting her and speaking with her as if she were a sick person. You don't want to be hurt by the sick person. Nor will you participate in what adds to the illness. And you keep your visiting hours on a schedule you can tolerate.
The hardest part may be this: You expect nothing.
You visit her because you want to, because you get something out of it as it is.
The terrible things she says to you are part of her symptoms. Think of them as you would a fever or a rash. They are not about you. They are about her situation. You can leave. She can't.
She doesn't have a choice except to behave as she does. You have choices. Yes, this would be much easier to accept if the person were a stranger or a hospitalized person. She's your mother.
I altered the title of my article based on your letter. The bridges we build are to give us access to understanding. Understanding can free you and allow you more choices.
If your real aim is to free yourself of suffering you need to use your deepening understanding to guide you to new behaviors and attitudes. Then you can let of of expectations that snare you into endless frustration.
Please, Shh, let your goals be about you and how you can live your own life as you wish.