I know it could be really frustrating when you're in the situation. Try to stay away from her. Usually when people are like that to others, they are fighting with themselves inside. They usually aren't happy with themselves and they don't know any other say to deal with it than to take it out on others.
Please, I beg you, don't let it get to you. Know that you're not the problem, no matter how much she tries to make you think you are. It's not worth it.
I hope your situation gets better! You're doing a great job! Keep rockin! :D