I'm not sure what to say because it's quite a long post and there are a multitude of factors involved here with your mother. The sad reality is, you can't change her and the way that she acts towards you.

You've developed some sort of coping mechanism to deal with her, but I wonder if it's serving you well? If it was, you might find yourself in a position to step aside from her outrageous behaviour and not let it eat inside you so much. A way to look at her and go oh well who gives a sh_+_. Tough one, because she's done this all your life and you've had no reprieve.

Can you see someone about this who might be able to help you through all of this?

I'm figuring moving out is not an option otherwise you would have done it by now.

What about finding a room share in a house so it wouldn't be as expensive?