AITA for calling out my brother for taking my stuff

Ok so a little backstory here, I've always had trouble with getting along with my brother. I'm only 18 now and he's 20, but as far as I can remember he's been mean and rude to me. I'm sure I'm not entirely faultless in our disagreements but most of the time from what I can observe I seem to take it much harder than he does. Right now we're both living in our moms house in the basement.

My brothers definitely taken stuff from me before so I don't know why this specific incident seems to be making me so mad. For example, a couple months ago I had gotten a new pair of expensive earbuds, they were the wireless kind that come in a case. My brother stole the earbuds, then lost one of the earbuds after not giving them back for a little over a month. When I confronted him about it he denied taking them at first and only after arguing about it for a long time and asking that he buy me a new pair, he offered to buy me the cheapest used pair he could find. Eventually my dad intervened there so I ended up getting a new pair but I felt powerless in the situation. Some other examples of him taking things where I didn't react so much because I had become used to it were when he took my credit card, bought about $400 worth of stuff on amazon, and didn't tell me until about a month later. Or recently he went into my room and took some of my prescribed ADHD medication.

Lately I've been trying to save money in order to pay for university so I've been bringing home a lot of food from work. My brother has been into bodybuilding for a while now and is always very insistent that he eats enough calories per day, this means that normally whenever I bring home food he eats it all himself. Last week I brought home 4 sandwiches and woke up the next morning to realize that he had ate 3 that night. I don't mind if he takes some food, so I talked to him about it and he said that he would only take "one serving" from now on and I believed him.

Yesterday I spent 2 hours baking cookies for a family event today. I made 26 cookies in total and then put them in a box in our fridge which was labelled "for grandma". I had asked him yesterday if he wanted any cookies and he said that he couldn't eat that much so I needed to break off ¼ of a cookie for him, which I did, and he seemed to enjoy it. This morning I woke up around 4am to go my job at a coffee shop and looked in the fridge to see that of the 26 cookies I baked, he ate 18 of them that night. This was my first time baking years and was very proud and excited to give them to people and I felt almost destroyed in a sense when I saw that.

I was probably unreasonably mad by this, and almost instinctively sent him a text message while he was sleeping, saying "Did you seriously eat all those cookies I had made for grandma? You selfish fucking brat". After some reflection I still feel upset over the cookies but feel really bad about that message and I feel as if it was uncalled for. Am I out of line or was my anger justified?