I was in the same position as you when I was at school. When I was 15 my family moved to a new area and I had to leave my old friends and go to a new school very abruptly. When I started at the new school I made friends with two girls (referring to them as A and B)who were in a clique of friends with these two other girls (C and D) and had been for a very long time. C and D, especially 'C' who was the leader of the group didn't like me at all for no/stupid reason and were upset that I was disrupting the 'balance' of their friendship group and interested in being close friends with A and B as according to C - girls A B and D were her best friends only and she was very possessive and controlling over the group.
The group of girls always did things together but never invited me despite A and B being the nicest to me because C and D weren't having it and hated me. Whenever we hung out at school, C and D would make comments to me like 'why are you always here?' and 'find your own friends' whilst laughing them off as jokes. When we had lessons, if I was in a class with girl C or D they wouldn't associate with me at all, and I would only be hanging out with them if girls A/B were present with them. They also all gave each other birthday and Christmas presents but I never got a single present or card from them.
In short, I was only a follower and they never saw me as a real friend or friend worth keeping despite A and B being nice to me. It took me until I left school and none of the girls contacted me ever again yet still hang out together as a group to see that these girls never saw me as a close friend at all but merely a tag along. A and B were closer to being friends with me but it seemed like they were scared of upsetting C and D by inviting me out, including me, sticking up for me against them and not treating me like I'm invisible as C and D were quite manipulative. The fact that they never did showed me that even they weren't real friends to me. But then I went to uni, met tons of new people, started work after graduation last year and I have found through uni and work loads of wonderful new friends who don't treat me like crap. So I would say hang in there. Ditch these 'friends' as it's better to be alone than to hang around with fake friends and users and focus on making new friendships. It will get better.