New school- now friends with bullies, uuum what should i do?

okey so i just moved to a new school, and it tiny, only about 100 people in the school, and there is only one group of girls around my age, who i get along with realy well. but there is this one girl who i think is autistic(im not sure what its called but i think it sounds like that and its where they dont understand body language verywell and stuff?) and when she tries to get into the group people are just rude to her and she doesent every take the hint- i realy want to be nice and include her and ive tried and everyone is fine but after one of them told me 'ok your new and your realy cool and nice and stuff but you just cant let her in- shes done stuff' is there anything i can do? because i realy dont want the remainder of my highschool life to revolve around homework and looking at pictures of mangled bodies online and dreaming about the day i can let loose with a machine gun. but i also cant stand being mean.