AITA for not sharing food with my nephew?

Hi, I(19F) know my confession is not related to the game but I know for sure that this community will help me understand the situation better and resolve it because I have seen them do that during the last few confessions. I don’t wanna reveal my name because I am not that brave enough lol. 

I have been cooking dinner for my family for a few years and we take turns cooking. Dinner is something I enjoy cooking after a hectic day at work and I know I’m good at it. I really don’t mind switching places with my step-mom or dad whenever they offer to cook because I would consider it a break day and enjoy having it with my parents. 

My step-nephew(10M) has come over for two weeks and he has been really sweet towards us. But he is a picky eater so we always make sure to ask him what he wants to eat rather than thinking about what others like to eat. But that’s okay I guess, we manage to eat it no matter what. Well, last night, I was super exhausted after work and didn’t feel like cooking. So, I asked my dad if he can cook dinner instead of me and he happily agreed. I was really craving some Indian food from a nearby restaurant and I told dad to cook to for others and leave me out. He sweetly offered to pay as well, but I obliged since I was all set to order and pay for myself instead of being a burden to my dad. 

My dad cooked meatloaf for everyone because he knows that I don’t like meatloaf and my nephew loves them. My food got delivered as soon as my father finished cooking. So I sat down with the family since I did not want to be alone in my room. My nephew suddenly decides that he hates meatloaf and loves Indian food (which he doesn’t because he had given it a try before and absolutely hated it, he just liked the idea of curry). He threw tantrums, yelled, cried, and threw hissy fits to have my food. My dad and step-mom both just said to give my food to him and eat the meatloaf served to him. I really got frustrated as they know that I don’t like meatloaf and also that I had a very hectic day. I just told them to back off and let me enjoy my food. 

They just gave me a stare and asked me to stop behaving like a child and give the food to him. I finally gave in and gave my food to my nephew. One bite and he spat it out of his mouth onto the rest of the food. I couldn’t see it anymore and frustrated, I went to my room crying taking the chips kept on the table and ate them as my dinner. 

My parents then come into my room and yelled at me saying that I need to grow up and that if anybody should be mad, then it was them on me for being mean to my nephew. And my dad tells me that I am a spoilt brat and I need to stop. Am I wrong here? Tell me, guys.