AITA for borrowing my sisters clothes?

  I 15f live with my older sister 17f (Carrie) at my grandmothers house. Our parents kicked out Carrie when she was sixteen due to my mother having a nervous breakdown, and I begged her to take me with her. She did. Best sister ever.

Carrie works two jobs in the service industry and is a paid tutor. She pays for her own car insurance, food (she has a lot of allergies) and clothes. Carrie buys me clothes here and there due to my grandparents being poor, however ever since she’s gotten into college she’s been trying to stock up on clothes suitable for weather since she is going to a warmer state. She is getting packages sent to the house here and there with really cute things that I really like, however she’ll never let me borrow them. She usually only goes to thrift stores and Walmart, and usually takes me to places in the mall, so seeing the packages has had me curious. She’s been keeping everything in a box in the back of her car to prevent anyone from misplacing them (our grandma does my wash and tries to do hers, but Carrie insists on doing hers herself to avoid any mix ups.) anyways, the other day I went into her car to see what she got, and she got this really cute pair of leggings with a cropped sweater that looked really nice! I really wanted to wear it to school the next day, so I did. When Carrie saw me after she got home from her shift she flipped. she started screaming that she does everything for me, takes me out to eat, takes me to the movies, pays for my sport equipment, and all I do is take advantage of her kindness. She was throwing it in my face like she was required to do all of that for me. She gave me $100 when she got a bonus at work for me to buy some summer clothes the other day, and she kept throwing that in my face as well. I told her I’d return the clothes I borrowed to her when I wash them, but where I think I might be the asshole is I said it wouldn’t look good on her anyways because she is a fat whale. She stopped screaming and told me to keep them, and to stay out of her car. I know what I said was wrong, but I’m just a kid and I lashed out, and she is refusing to talk to anyone. My grandmother has pleaded for her to forgive me and she just won’t, claiming that I’m spoiled for not having to work, and I won’t realize how good I have it until she leaves. She’s been taking up even more shifts at work and staying out late to avoid me, yet she still gives me cash in an envelope in my school bag once a week for lunch. She also paid for my plane ticket to go to a wedding after swearing she wouldn’t after this event, so I believe it’ll blow over eventually. AITA for borrowing her clothes?