Indeed, her other friend may be right that cause you are not interacting with her that is making her worse, however it is your right, for whatever reason you decide not to interact with anybody you dont want to and that is something the other party simply has to accept. I dont feel you should have to interact with anybody who makes you feel uncomfortable or scared, that is wrong. If you have tryed to contact her and help her understand how you feel and it brings no solution to this problem you may have no choice but to involve the police, eather that or live your life in fear which is not right for you.
You former friend has issues, she needs to deal with them by herself, it is her who pushed you away and i think in her head its all your fault she feels this way. This is dangerous for you, it has to stop, I think maby you should meet her face to face, in a secure location, with others nearby and talk things over, afterthat, if your former friend cannot deal or treats you badly, its time to involve the police plain and simple, things can spiral outa control quickly and Id hate to have you get hurt or in trouble. Its good to be a friend and try to help, but I think you have done all you could at this point and you should be enjoying your life, not living in fear.
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DX'ed with HFA as a child. However this was in 1987 and I am certain had I been DX'ed a few years later I would have been DX'ed with AS instead.