Ok stick your right index finger into your mouth. Now...bite down. HARD. Did it HURT? Well of course it did honey because you're HUMAN. God I cant tell you how many times Ive lost it with my kids and said stuff and did stuff I regret and for years afterwards thinking about it still makes my stomach knot up. But the kids dont feel the pain that we think we inflicted on them. We do because we love the little buggers and are always trying to protect them from abuse so when we do it ourselves...well its just inexcusable and unforgiveable. To us anyway. You said you were sorry...dont beat yourself up about it. Teenagers are put on the planet to push the envelope and test our metal. No doubt about it. I have an 18 year old boy an almost 16 year old girl (add PMS) and a 12 year old boy and my mind as this board knows...is turning to MUSH with all the pressure that ensues. But on the other hand, kids have to learn somehow what the boundaries are and if they are pushing you to saying and doing things you ordinarily wouldnt then a point has to be made that they are out of line. If you poke a bear and poke a bear and poke a bear and he turns around and rips you up you cant be pissed off at the bear.
She might not think so but perhaps your telling her Fuck YOU! struck a cord somewhere deep down and she will remember that she was biting the hand that feeds her and think twice about it before doing it again. She will remember how she acted towards you when she is confronted with seeing herself in her OWN kids. That...is the sweetest revenge :)