its never fair, but in the end the one who started the physical attack first will be the main culprit no matter the reason.

i had almost similar incident like 8years ago in school. i was the one bullied even though i was much bigger size, was known to be a cool headed and friendly guy. but sometime it took its toll, and one day when going through the same routine, landed a few punches on him and had him running away. it was after school, and he did not report to anyone. heh.