I don't know what to do

So last year I was a loner in school until I made the effort to socialize this year. I wouldn't say I'm popular but I'm not unpopular. I'm in the committee for one of the clubs I'm in. I'm in two cliques, one made up of two other people in my grade with the rest made up of people in one or two grades above me. The other clique is made up of people from my homeroom, and that's where my problem starts.

I found out from one person in that clique that the rest of the group really hates me, and I'm really annoyed that they didn't tell me in person. But the more I think about it, the more it makes sense because they've been giving me the cold shoulder recently. I feel like I don't want to hang out with people who don't like me and I'm planning to study alone in the school library during free periods since I have exams everyday for the whole of this week anyway. I don't want to stick with them anymore of this is what they give me for being nice, so I'm done.

But inside I'm really hurt because I feel like I trusted them too much and I still care deeply for all of them except two (long story, and the hate is mutual) I don't know how much of this is true about my friends hating me, but it can't be ruled out as a possibility. What's worse, I have three of their birthdays coming up next month do I'm not sure what's the appropriate thing to do. But most of all, I'm just really hurt and lonely. I can't be with my other group because they're busy studying and those two grades above me have their finals.

Sorry for the long post and I appreciate anyone willing to help me out