Agree with pretty much everyone else here. She is making her own mistakes. Can't keep someone from doing that. Be there for her. Let her know that you love her and you don't condone her hitting her mom and getting in trouble. And that you don't like it, but that you're there for her. Be calm too dude. Like Plunkey said about the "pack leader" - lol - really though, she needs to see that you're not flipping out, but you're reaching out. You flipping out and getting angry will probably have the opposite effect you want it to (drive her further away into negative behavior). Be calm and assertive, firm but gentle. She will come back around.
We all go through things. Think back to when you were a kid. I know doctors who, as kids, smoked weed, had sex protected and unprotected, got pregnant at 16 and had an abortion, got arrested, etc. Yet still they managed to get excellent grades, go through 8 years of college, and become positive, successful contributors to society.
Relax. Take some deep breaths. Think about how much worse it could be, but come back to focus on the positives.