Hi OP, I'm sorry you're having to go through this. It's hard to maintain your composure when your mother goes out and actively paints you in a bad light, when you were as kind to her (probably more than she deserved) given her treatment of you. Her type of person actively stomps on your buttons hoping to provoke a response from you, to drag you down in the mud so she can wrestle with you.

I agree with the advice to ban and block. For the inevitable flying monkeys that creep through, could you create a script that you can refer to (usable for in-person, phone, text, email, etc.)? Maybe a second one for more innocent people who you want to keep in your life that may ask questions, not realizing it's a hot button. Pretend you're giving a press conference, the kind where you are in charge, you zip in, you make your statement, and say "That's all we have time for today" and leave, so they can't pull you into JADEing. Writing it down may help to keep your wording consistent; toxics sometimes seize any change in wording as the door being open a crack to more harassment.

Re what your mother's friend did - oh the gall. Try thinking of the really bad flying monkeys as scummy lobbyists - they're pushing someone else's agenda. Good for you for shutting her down.