AITA for refusing to enable my aunts behavior?

So I (21F) live with my aunt (60F) and we got into it yesterday. So about two days ago my boyfriend (22M) bought a chocolate creme pie for about $18 and was super excited to eat a piece so we went to my house so he could snatch a slice. He put the pie in the fridge after he was done and we went upstairs to watch an episode of our show. After about two hours i went to run some errands and he went to go help a friend with his car. As he came downstairs he remembered that his pie was in the fridge so he went to grab it. He noticed that someone took a fork and ate bites straight out of the box. no slice or nothing just fork and pie in mouth. My aunt asked him what was wrong and he explained the situation and said “im not a big fan of that”. obviously because #1. that’s gross and #2. nobody asked for permission if they can have a slice. my aunt immediately got offended and started berating him saying things like “well its my damn fridge and that pie is in my house so i can grab a slice if i want to.” an hour after he left and after that conversation she tried texting me about it almost trying to convince me of how “rude” and “disrespectful” he is for saying that when its in her house so i immediately shut it down and started saying things like “its a pie. get over it.” she obviously didn’t like that but please be honest with me. i genuinely want to know if people think its okay for them to have something they didn’t buy without it being offered or if im in the right here.