Please help me! my group of friends are falling apart! this is serious please help me!?

ok so i have a group of tight friends, Rachel, Tiffany, and Teddi. Rachel and me have been friends for 3 1/2 years, Tiffany 6 months, Teddi 1 1/2 years. okay, so tiffany came and she was new a few months ago and our headmaster mr.rish asked rachel to show tiffany around the school. well at the time rachel had been crushing on this guy one grade higher named caleb. caleb just so happened to be tiffany's cousin. anyway me and tiffany hooked rachel and caleb up. so anyway rachel changed alot. here's the problem. okay, so tiffany starts to exclude teddi in secrets games and everything else so they are always fighting, so teddi starts sitting at a different table and tells me and rachel that she's not mad at us, but will not hang out with us as long as tiffany is hanging around us because her and tiffany had been on and off fighting ever since tiffany came. then 2 days ago i was sitting at a wooden table at scool during our break with rachel caleb and caleb's friend ethan. so i started laughing so hard at a joke ethan made that i started choking on my coke. so rachel starts patting me on the back, but really hardly and i almost fell on the concrete. so i was like "what r u duing?!" and she was like � wan't doing it so hard". so i go to the other side of the table with ethan and i told them i wanted to leave the table and so my pocketbook was still on the other side with rachel and caleb. then she tells me that she doesn't want me to leave and i'm like "give me my pocketbook" and she was like "no i don't want you to leave" and i'm like "give it to me now" then she starts yelling (she sounded like she was playing around and being serious) and she was like " here , just leave" and she threw the pocketbook on my arm. and i'm like "ow" and she's like "how could that have possibly hurt you" . and so we didn't talk for the whole day. so the next day i went to talk to her in the lockerroom about the teddi and tiffany situation. and she ignored me. then the day after (yesterday) i went to talk to her about something or another and she ignored me. so i am pretty fed up with it all. our friendships are pretty much fallen apart. i can't be around rachel cuz she's stuck up now, if i hang out with teddi, i can't hang out with tiffany, if i hang out with tiffany i can't hang out with tiffany, if i hang out with teddi, teddi can't hang out with rachel, iff. . if.. gosh, how is this ever going to work out? we can't be a group anymore. what am i supposed to do? we only have 1 more day left till' summer and how in the world am i supposed to fix this? i'm gonna cry all summer if i know i can't hang with my friends without everyone arguing and hating on each other. (me included) what do i do? i don't want to apologize , b/c i've apologized so many times when i haven't even done anything, that i'm fed up with apologizing for something i haven't done. help!!!! please!!!