Help me! Friend issue! It's really bothering me! My emotions are going crazy!?

My friend has been acting strange lately. I transferred schools in the middle of the year to be with my friends, the people in my other school were horrifically mean, not to me but you know what I mean. Me and this friend were so close last year, and in some ways, we still are. But things have been getting weird. Sometimes, and even other people find this too, she'll ignore you if talking to someone else or a group with her other friends. I find that I can only really get through to her when I'm in a small group of only our closest friends, or alone with MAYBE one person, and that person is very like me. This close friend and her talk about things that occur at school, and the friend that i'm having this problem with tells my other friend secrets and gossip and stuff, and leaves me out. Normally, I wouldn't care much, but they talk about it around me they either IGNORE me, quite rudely, or the friend who is like me will tell me that my other friend said "she won't let me tell you," or "SORRY, I'm not ALLOWED to tell you." This may not seem hurtful or I may seem selfish but this gives me a lot of pain and grief. The fact that they will continually talk about something I don't know as if to rub it in my face hurts me. It hasn't just happened 1-2 times, it happens almost EVERY DAY! When I tell them how much it hurts me, and I don't really go to much extent, they either just give up and tell me (the friend who is like me who cant tell me, and rarely the other), but this doesnt make me feel any better whatsoever, or they just blame me for doing something wrong or state a reason for not telling me that is not rational whatsoever.(this has never been the friend like me). When I do find out stuff, this friend that is similar to me ALWAYS finds out first, leaving me feeling left out.If you don't understand the extent of this situation, I have cried myself to sleep, stressed about it in school, had nightmares about it and lashed out at my family for it. I dont want to get hurt anymore, and I still want to be friends with these people because besides this, i love them. It's really just this that bothers me. I REALLY don't know how to handle it, or what to do. I need help! Please give me advice! I'm begging you!