in high school, the first rule is that popular people always win. she looks like shed be more popular then you. therefore leave her alone or you will lose.
theres a reason they make movies about less popular people coming out on top, its because it never happens.
leave her alone. stop listening to her conversations, stop interjecting yourself into her conversations. and let her treat you poorly.
even if you come out on top with teachers, you will lose in any social setting and end up taking your cousin to prom. nobody wants that. except for her and her popular friends so they can laugh at you more.
this is good advice.