I have to figure out how to make things right with me twin

I got some hate on my post about how I thought my twin brother stole my flash drive. He needed it for his summer school and mom made me allow him to use it. When I asked for it back he looked for it and couldn't find it. So I was pretty sure he stole it. To get revenge I scared the shit out of him. He has an extreme phobia of clowns. Just seeing one throws him into a panic attack. So... I stole the clown mask our older brother has and scared him when he was asleep so bad he pissed himself in his bed. My mom had to calm him down and grounded me. I also told him I was gonna tell my friends. I'm friends with a girl he likes so he begged me not to tell and I was having fun with it... Until I found my flash drive in my own room and remembered picking it up off the table... I told my mom I found it in my room and she upped my grounding from 2 weeks to a 1 month and said I better apologize to my brother and hope he doesn't start wetting the bed again.( he peed his bed until he was 14). So now I gotta figure out how to apologize to him. One thing I don't understand though is why I can't just apologize and why I had to get an extra 2 weeks of being grounded.