Have i done the right thing?!?

I had a really good friend who was girl (not a girlfriend) and we have been mates for ages. But for the last year people in my school have been calling her names such as fatty (as she is a bit overweight) and terry (cause she wears alot of make up and sghe looks ORANGE and terry is from 'terry chocolate orange' and casuse dawn french ios the face). She has been two faced to all her mates including me and one of the boys at school had a go at her and she started geting violante, and my whole year (year 11) was watching and she went to hit him and so i pushed her and shouted at her. and she called me a prick so i said to her *** off. and i dom=nt speak to her also i hang out with the popular people in my year now, who call her names, and i stuck up for them and not her. Did i do the right thing?