you have a right to tell her how you feel and that you would like to discuss it in person and as calmly as possible. And when she is ready to come over and converse then you two can discuss what needs to happen to make your relationship better and if that included her going to therapy (I would bring it up to her again, maybe mention it to her that you are contemplating talking to her mom about it) set some boundaries you need to have a healthy relationship for the both of you. Make it clear you will talk to her when she's ready to come over and talk to you if that's what you feel you need to do. Don't feed into her behaviors that aren't healthy. But in the end any help for herself has to come from wanting it for herself. Can't make anyone (well we can't ) want to do anything they don't want to. And if when its all said and done things don't work out you gave it your best shot but you are young and there are others out there so either way things will work out