Omg i think i kill someone?

ok so the 4th of july this guy bought me a bottle of drink and everything was cool so my other friend came and bought another bottle of the same drink and we were drinking and everything.. so we ped the first guy that bought me the bottke with the other guy and he tought wew was going out (but we wasnt just cause he bought me a bootle of alcohol doesnt mean were going out)....so i was feeling sick cause i drank to much and went home to sleep then my friend called me and told me that the guy tha first bought me the drink fought him cause he thougt i was cheating on him... so my friend got mad and shot him and the guy that first bought me the alcochol bottle died.. omg i just can believe this i feel like this was my foult.. :( what can i do now?!?!