What do I do if I was charged with aggravated battery if I never did it?

Two of my friends and I were riding 4 wheelers on a dirt road when approached by a man in his car who slung rocks on us, got out and attacked one of my friends after yelling. He paid to gravel the road even though the road is public. Two of my friends tried to fight the man off which resulted in injuries to the man. No witnesses were present until a man from the home which we were in front of heard the commotion and came running with a rifle to protect his friend at this point, I jumped on my 4 wheeler and left while my friends and the man were still fighting. One of my friends ran from police while I and the other friend went into the police station to answer any questions. At that time, my friend was arrested for aggravated battery for hitting the man even though he was defending himself. That has to be proven in court. I however never so much as said a word to this man which is what I and my friend told police so the let me go. However, the next day the investigator called and put out a warrant for my arrest stating he had new witnesses claiming they saw me hit the man and now I'm being charged with aggravated battery just like my friends.