I 19f share a bedroom with my sister 14f. She recently got a new bed so our mother took us shopping to buy new bed sheets. I bought some green ones with plants on, my sister chose purple. Her favourite colour is purple and she got her way when we had the room decorated years ago. Purple walls, purple curtains. Well I wanted to buy a green Valance sheet to match my duvet cover, my mother told me no because it wouldn’t match the room. She wanted me to get purple or pink. I said no, that I didn’t like purple and that it was bad enough sharing a bedroom that I can’t decorate to my choosing but I wanted my bed to be my colour. She insisted on pink valance sheets for me and my sister so I told her fine, I would buy the green one myself. She then called me a cow ect and said that I ruined everything and to go put the pink ones back and buy two green ones. I said I didn’t want to match my sister, I wanted my bed to be my own since the rest of my room wasn’t. I ended up buying the green myself and the purple for my sister because she didn’t even want pink either. We caused a small scene in the shop and she is now giving me the silent treatment. My mother is emotionally immature and I’m her least favourite child, middle child but oldest daughter, and she loves to argue with me.
Am I the asshole?