Not only that, she threatened to kill all my friends just for being my friends... And she's one of the most vicious people at my school, so knowing her, she probably would too... She's already beat me up several times before, now she wants to kill me! To make it worse, the administrators of the school don't care about bullying or anything like that, so nothing will happen... I don't know what to do... :'(
If you are seriously worried about your own cousin, you should talk to your parents.
And if you think the threat is serious, then I would call the police.
If she gets a warning, she will probably get a reality shock.
PM me if you need any advice. :/