That's... That's just horrendous, Blue...
I have to agree with Obo, next time you see her, give her hell. What she's doing to you is wrong, it's wrong on every level, any way you look at it. And make sure your dad, your caretaker, whoever you can trust, make sure they know how you're feeling. Talk to someone you know you can trust, be it a relative, or even a councilor at school. Someone other than us, who can help you out. We're always here for you, you know that, but we can't help you out in real life.