Me (13F) and my sister (16F) have always had a strange relationship, she would ridicule me and make fun of my body and what I eat everyday, it has been happening for years now, at home, by family and at school by friends so it really got to me, I felt insecure every time my sister was around, and she was a really slim girl and showed her body of all the time, she had made me so insecure that I developed what I think is an ED as I began to skip meals and even go days without food. I really hated her sometimes and the thought of her seeing my body made me feel sick.

Last week our family was getting ready to go out for food which we never did and so I needed to shower before we left, my sister told me to hurry up because we needed to go to the shop for an energy drink before we left, I was showering and my sister knocked and said to hurry up, I said okay sorry and tried to hurry in the shower, around 3 minutes had gone by and I was nearly done, I was getting kind of hot in the shower and decided to open the curtain a bit (it was open enough for people to see my full body at the door but it was closed and people knew I was showering we just wasn't allowed to lock the door) so I thought I was fine, when all of a sudden my sister burst into the bathroom shouting at me for taking to long. I froze and was so mad, I shouted at her and told her not to walk in on me in the bathroom to which she said 'don't be dramatic we're sisters' and that's kind of understandable but she was the one sister that always put my looks to shame, plus I'm 13 and still growing and developing so I really hated her having to see me naked, she left the bathroom I rushed out of the shower and shouted at her, we had a screaming match about it and my mum said that we 'ruined the whole day for everyone.'

AMTAH for getting mad at my sister? Was I being overdramatic? What should I have done instead?

Edit: thank you for your opinions on the situation! I just wanted to make it clear that I couldn't lock the bathroom door because my mum doesn't think it's safe to lock the door whilst showering but my whole family knew I was showering as I told everyone just for the very reason that I didn't want anyone to walk in. Thanks for your replies and support guys !