hey, i understand your situation...
you shoudn't let his sister and friends tell you that you are not welcome of coarse you are.. go there and if they get in the way walk right threw them... go see that guy i tell him you are there when he needs you even if you guys arent talking... make him feel special and help him out. he'll understand you care lots bout him and he'll wont be so stubborn (well dont know the guy but if i was this guy and you did that i wouldnt be mad at all) ask what happened and tell him its not his fault (if he was driving)... i cant tell you every to say if you really care for him dont worry you will find the words....
p.s this isnt a stupid question and why did you start to fight in the first place..