Assault & Battery: Massachusetts assault and battery charges

hi

i live in massachussetts and about a month ago i got into a fight with a guy that i know well and that knows me well. at the scene there were 2 more people, one of them was the owner of the house. The guy and I got into an argument over some money that he ows me, and while arguing he said he will never pay me back so I punched him and broke his cheekbone. After we left the scene he went to the police and reported the incident, therefore the police never showed up at the scene. I received a letter in mail which states that I have to show up in court, and that I am being charged with assault and battery with weapon. I did not have any weapon, I just hit him. He is claiming that I hit him, and one of the pople that was at the scene is his friends that lives with him, therefore he is a witness, but the owner of the house where the scene happened is my witness. i'm planing to denay the whole thing

what do u think i should do??