AITA for calling my brother a f*tass because he ate my dessert?

16F writing this and i wanna know if im overreacting.

Basically i went to school this morning and the day before when i came home i bought tiramisu and was planning on eating it today when i got home after school + work. My brother 22M eats everything in the house so much up to the point where when my mom cooks she makes an extra pot or whatever just for him and i told him nicely before i left today that the tiramisu in the fridge was mine and to not eat it and he said he wouldn’t.

I even put a note on it and stuffed it deep in the fridge hoping he wouldn’t find it even if he looks. And pls don’t tell me he wouldn’t have found it if I hadn’t mentioned it because he rummaged through the fridge almost every hour so he would have. I even sent him a text throughout the day asking if he ate it and he said no and that he won’t cuz I told him.

Well I came home an hour ago after working alone at the register my entire shift and after my exam at school, lo and behold it was gone. I burst into his room and started yelling at him and he told me there were no snacks in the house and he didn’t have money for gas to go and get some. I called him a f*atass and a glutton and he got really sad. My mom’s mad at me now and has grounded me for the entire weekend because I yelled at my brother and my dad keeps telling me to apologise because my mom won’t lift my grounding.

I mean I do feel bad for being mean to him but he eats everything. I’ve hidden snacks under my MATTRESS, in empty shoe boxes in my closet and even in old water bottles but somehow he always finds them and eats them. I’ve never been mean to my brother this way but he just pissed me off and I get it was mean but I’ve never finished a snack on my own in years now because he eats everything. I wanna apologise but I also wanna stand my ground because im DONE. Also sorry this was kinda a mini rant but AITA ?? Should I apologise