How do i get out of this SERIOUS problem? ?

ok , so i was gonna fight w/ a group vs some other kids but i befriended the other kids and now the leader of my group says i gotta pay back , i gave him 3 bucks snd a cig thinking it would work (i know its almost nuthing but u gotta try) now if i dont go to beat up this kid the leader of my group (i dont wanna be in it anymore , or fight ) is probably gonna beat me up , i dont feel safe , he has millions of weapons in his house and is the type of person that would kill u if u calked him a ******. i dont wanna be a part of this cuz its a lose , lose situation . how do i get out? HELP ME!!!!!!!!!!!!!!!!!!!!!!!!!!!