I cried for hours today:(

I have this cousin and all she ever does is bring me down. She lives on my street and is in my grade. All she ever does is say rude things to me and talk shit ab me to other ppl when I’m right there!! She’s always had a jealousy problem but i don’t understand why she has to make me feel like crap. She’s a bad influence and does drugs (were 16) and when i say no to doing them she makes fun of me. Today my friend road our bus and the whole time my cousin and MY BEST FRIEND (who is also good friends with her: long story🙄) we’re talking ab me right behind me! I started crying and my bf comforted me. When i got him i began to sob bc all i ever do is be nice to her and she controls my life! I don’t know what to do!