I agree with Skeezyks to end contact with her and stop being around her. Is there a way you can block her in streaming? Is this still something you enjoy? (Streaming) if not, then maybe consider 1.) Closing your account there or 2.) Going somewhere else to stream. Somewhere where she is not.
I'm sorry you're going through this with her. She sounds very immature.
My last suggestion, would be: take care of your mental health. Find ways to build it back up. Do things you enjoy. When you do, you may find a new perspective on A. Like that she is pretty pathetic and that you may feel like you made a mistake in dropping her, but its your choice. She sounds very unhealthy and harmful. Who wants to be around that? You did what was right for you.