When Should You Walk Away From A Friendship?

This person sounds emotionally abusive, almost psycho. She says one thing and does another and that alone proves she can't be a good friend to you or anyone. I'm a little older than you but I recently ended a friendship I thought was a real one, or rather found out why it ended. It was over petty stuff kinda like your story. The friendship you had with this girl seems very one-sided and I think its best you ended it. She threatened to end your friendship and got mad when you did exactly that. Real childish behavior. Real friends don't do stuff like that.