Damn You Girl

will someone please help me? it might be kind of long, but i'll be so grateful for the help, i really will.

there's a girl at my school, lets call her sandra and she hates me, she's never made any secret of it, i don't really know her that well, i sat opposite her in science last year and she was absolutely fine with me until a few weeks before the end of the year. i've never done anything to her and have never been anything but nice to her.

i fell out with one of my best friends the other day, lets call her jenny. well jenny and i had an argument because i asked her not to add my brother on facebook and she did. stupid argument i know, but it annoyed me. we're ok now i think.

on MSN tonight, sandra says to me "i heard that you dont like people adding your brother on msn, so i added him

"
me being fed up of not knowing why she hates me, i asked her why, she said that its because "i'm a b*tch to jenny" and she said that the other reason is that "its just YOU :L"

i'm sick of this, i've been in tears tonight and while i'm typing this i'm physically shaking because of it, i fell out with jenny again yesterday because she had a go at me over something stupid, and sandra being horrible, i can't go anywhere in or out of school in case they're there. i hate it so much, what am i supposed to do? someone help me please?