What will happen to my daughter, she's being charged with assault from her school?

My daughter has been verbally bullied by her former best friend for over 2 years. I spoke to the mother of the other girl and she told me to pretty much "F" off and its just middle school crap and let them deal with it. After that I spoke with the school counselor for make a formal complaint and she spoke to the kid and parent. But the snickering and dirty looks continued. Last Sunday at the beach with her friends the girl was her with friends and called her bad names in front of my daughter friends parent. Monday came and my daughter tried to talk to her and she blew her off...let's say my daughter snapped and gave the girl an *** whopping. What's going to happen now?