AITA for canceling a party because of my mom’s prank?

I’m 17 and I have a brother who’s 15. His birthday was yesterday and he wanted to have a party for it, his first ever party. I had a party for my birthday when I was 16 but I wasn’t allowed to invite anyone and it was boring as hell.<br><br>I felt bad for my brother so I decided to throw him a surprise party. I got all the planning and everything ready weeks before his birthday and kept it a secret by only telling his friends. The party was all set to happen yesterday when he turned 15.<br><br>We live in a 3 bedroom house. My mom and dad occupy one room. I occupy another room by myself and my brother occupies another room by himself.<br><br>My mom played a prank on my brother the night before his birthday. She told him that I was bulging and needed to be taken to the emergency room so we could get the air out. My brother was gullible enough to believe it and was panicking. I was bulging but not for the reasons he believed. It was because of the party and everyone who was hiding at my friends house.<br><br>He followed us to the car and opened the back passenger door to get in. The joke was over at that and everyone came out and surprised him. He was super excited and couldn’t wait for the party the next day.<br><br>The next day, my mom told my brother to go to his room to get some rest. She told me to go to my room to get some rest as well. We both went to our rooms.<br><br>When it was time for the party, I opened my door to go to the living room but my parents and my brother were already there. The house was decorated, there were balloons and streamers, a huge cake, etc. It was a better party than the one I had planned.<br><br>My brother was crying tears of joy and said it was the best birthday present ever. I was confused so I asked my mom wtf was going on. She said it was her party. I was livid and I told her that it was the party I was throwing. She said that it wasn’t my party because she paid for everything. I paid her back and she let me take everything that was hers.<br><br>Me, my brother, and the decorations and everything went to my friends house. My brother was upset and didn’t want to celebrate anymore. I told him that I still had everything and we could still have the party. He said he only wanted the party if it was the one mom threw and he wanted to go back home. I took him back and we missed the party.<br><br>My parents are pissed at me for ruining my brother’s birthday party. My dad said that my mom went through a lot of effort and everyone was having a great time until I showed up. My brother is mad too because he wanted to keep the party that mom threw and he wanted to spend his birthday with our parents.<br><br>AITA for ruining my brother’s birthday and destroying the amazing party mom threw for him?