Why does everyone hate me?

ok so ders this group at my school that alwayss talk behind my back && alwayss give me dirty looks & when i asked them why are you guys talkin bout me der likee oh ur likee a sister & all this other stuff so one day me & my friends left school & when i came back i got in trouble they showed me the video of us leaving so we all got in trouble one of the boys that was with us was the girls brother & then she & here little friends started makin statusess about me on fb sayin im a snitch & dey want me to kill myself ever since den everyone started hating me whats wrong widd me??