Please help. I am in serious friendship trouble...?

Ok so here's how the story starts: my bestest friend in the whole world and i are just having a great time. Then (trying to kinda keep this short and simple) she becomes really good friends with this girl ellie and i start to feel left out. I try to become better friends with ellie... which then causes my best friend sandra to feel left out. Sandra becomes close friends with some girls who already didn't like me (not sure why but just go with it). They start to be mean to me saying that i made sandra cry (which i had NO intention of doing AT ALL considering the fact that nobody, including sandra, had told me she was mad at me). So then, having lost my best friend and having multiple people mad at me for something they weren't even involved in, I decided to cling to ellie. Ellie and I became great friends because she was there for me. So then a few days later i decide to apologize and talk to sandra. We decide to try to be friends again. Then today i find out that she disabled her Facebook account and was mad at me YET AGAIN because she felt like i was excluding her for ellie. I understand if you can't find a solution to the whole problem but maybe if you have any advice i would really really appreciate it. Thank you very much.