AITA for not giving a cupcake to a child who is not originally on the guest list

I (24f) recently returned to my hometown after being away for college and work. My grandma often hosts potluck party where her 3 kids and their families can hang out. I am a pretty good baker and the couple of times I brought baked goods over, I got lots of compliments especially from the kids. <br><br>For the potluck we had last week, I had promised to make a cupcake for a 4 y.o cousin, Emily, whose favorite character is Peppa pig. I made a total of 9 cupcakes: 1 for Emily and 8 for my 8 nieces/nephews. Every cupcake was decorated with a different character and there was one extra in case someone wanted a second serving. <br><br>On the day of the party, one of my cousins, Chloe (19f), brought her boyfriend, Jack (6y.o.m) w/o informing anyone. He recognized the Peppa pig cupcake and wanted it. Chloe said I was being AH for not sharing when “I made so many”. We had an argument and Chloe and Jack left before things got ugly. <br><br>My aunt was very upset when she found out as she was the one who invited Chloe. She said I should have just let Jack have the cupcake since I made so many. Now my family are taking my aunt’s side and saying I was petty and selfish for not sharing. AITA?