I really can't add anything. You have to advocate for yourself and not let leaches like that own your life. If they do do something stupid as a result you can't bame yourself because if they were already that unstable something was bound to happen rather or not you did anything to make them feel bad as someone else could just as easily.
I wouldn't dismiss the possiblity that she may be romantically interested in you either. Lets see . . . She is following you around like a puppy, ignoring everyone else when you are around, telling you about sexual experiences that she has had with other girls . . . Yeah, that seems like some signs to me. It could all be circumstantial but I wouldn't dismiss the possibility that that might be what's going on.