I'm Not Sorry About My Sibling's Broken Laptop Keys

So here’s the deal. I’m the youngest of three siblings and basically grew up in my older brother Max’s shadow. He always got away with everything, always had some excuse for his behavior or a way to spin it so he didn’t look like the asshole. But when I finally caught him red-handed doing something really bad one day, well...let's just say karma was on my side. It started off as a prank war this summer. Max had taken an old computer out of storage and set it up in his room for some project he’s working on. Now, being the youngest, I’m not exactly thrilled with how much time he spends holed up in there, barely coming down to eat or socialize anymore. So one day, while he was away, I decided to mess around with his computer keys. Took out the W and M keys, you know, just because they spell a certain word if you hit them together. I expected him to get frustrated at first but then laugh it off and figure it out himself. Instead, when he tried to type something important for this project deadline coming up, it was all messed up. He couldn't even type 'welcome' without hitting the missing keys by accident. Max ended up flipping out big time, shouting about how his work is suffering because of me. Now here's the twist: I found out later that his professor had called him into her office already regarding this project, saying it wasn’t good enough yet. He’d been trying to cover it all up and act like everything was fine. When he started seeing errors pop up because of my little key prank, well...the stress got to be too much. So yeah, his laptop keys were a casualty in our prank war but I didn't mean for this to go as far as it did. Am I the asshole here? Should I feel bad about messing with his stuff when he’s already stressed out about school work? Or is it justified that sometimes you just need to stick up for yourself and get back at those who always seem to be getting away with everything? Your thoughts are appreciated. Do you think what I did was too much, or do you feel like it was a fair play in our ongoing sibling battle?