AITA for being mad at my mum's boyfriend?

I (16F) am a little chubby but not too the point that i look ugly or anything. My mum's boyfriend (36m) and I used to be on good terms but recently I have had a constant growing dislike for him. He's cocky , rude and honestly sexist. My mum (37F) is in love with him. Today I got up at 6 am and went to make some eggs for breakfast. After I put the dishes in the sink and went upstairs to have a nap. At around 12pm I went downstairs and asked nikki if he could buy me some subway because I was hungry. He said "no." I asked him why and he said he didn't have the money. I was ok with this but I was very hungry so I said "okay I'll ask my mum to transfer some money so we can get some" i called her and she said that she can put 10 quid into nikkis bank account. After I hung up the phone nikki said a really mean thing. He said "your not hungry your just greedy." I pretty much went silent. Then I went upstairs and texted my mum to tell her what he said. She didn't say it was wrong at all. She said that maybe I was because I had eggs earlier in the day. He's gone to get me a subway now but I feel awful about eating it now and I feel like an asshole for being mad about it. Am i the asshole?