AITAH for wanting my cousin banned from my house

My cousin (14F) always annoyed me (16M), but its getting worse in recent weeks. My sister constantly wants her over, every weekend so she comes, and my family has to oblige to her taste, which includes no touching meat (even the package or the package of a package containing meat), you must wash your hands if you want to touch something she's might even breathe near, no burping, no farting, despite herself constantly doing those things.

She used to never be like this and suddenly decided that she germaphobic. I with a reasonable amount of evidence call bs, but nobody except our grandmother supports me, especially since she used it as a way to never see her dad again. In my opinion, she did this because her dad was less wealthy than her mother and stepfather and preferred that house.

Today I simply said my Halloween candy made me feel a little sick, and she bolted upstairs to tell my sister I was gonna throw up on her. Not only that, afterwards she started saying I was calling her a slur and a bunch of things. She also tends to make fun of me alot, around 20 times a day to my face, which means she must be saying much more about me behind my back, including fake rumors.