AITA?

(Sorry for the errors, I don’t speaking English)

Aita for saying that my 2 cousin is a fatass, insulting her and that she should come back where she’s from?

I, 16 F and my cousin 12 F, the oldest have Don’t get me wrong, when my mother told me that my cousin were gonna come live with us for a while I was excited, but the more she spend time in our house, the more my own safe space became hell. It all started with her touching my stuff, My key rings started disappearing one by one and when I confronted her about it, she said she lost it while bringing it at school to show her friends or when she touched my Kpop cards from an album, guess what ? She lost half of it at school too, I managed to find the rest in her school bag, all of them in bad state. I told my mother and hers about it, fortunately she stopped. I thought that it was over and that I could have my peace again but I was wrong. Next was the food, she would hide food that wasn’t meant for her next to her bed and eat it when everyone was asleep, My mother caught her by finding the cakes packaging while cleaning her room. Even tho she got severely blamed for that, she didn’t stop there. Instead she changed her tactic, eating MY food because I don’t know how to spot the difference. First it started slow, like eating one or two pasta that I saved in the fridge, but then she got too comfortable. Like this one time when I saved up lasagna for an other day and when I went to get it half of it was gone and there is no excuse because my name was written and the plate clearly visible. My last straw was when she ate my waffle, I made them for me. I know I sound selfish making waffle only for me. I made 5 mini waffles for me, I just went out with my friend for ONLY 25 minutes, I came back, only 2 waffles remain in the plate. I crashed out, It felt like she was targeting me. Making me purposely mad. I confronted her, Telling her why is she doing this. She denied everything, I wanted to grab her and slap her across the face but I couldn’t. My logic is , if I can’t use my hands then I have to use my words. I said that she was an fatass ,eating like a freaking pig and at this rate she will become the fattier version of the old NikocadoAvocado (An mukbang youtuber..) That she was a big, fat liar, she should return where she came from because in this house nobody would miss her and her parents probably sent her here because they were scared of her finishing all the food supplies. After that speech my mother punish me and I couldn’t go out with friends until I say sorry to her, I never did and will never ,I understand that what I say could have hurt her but she ask for it so I gave it to her. So, AITA?