LOL,
OK, now I know where you got your nickname.
I say good for you. It doesn't sound like you lost your "serenity" at all--you gave someone a long-overdue telling-off. The only thing that MIGHT have been better (or maybe not, hard to say) is if you had said something when he first started with the off-the-wall gripes. I'm sort of like you, though, I HATE confrontation--especially with a neighbor or someone else you can't completely avoid. It does tend to explode when it gets bottled-up for too long.
I wouldn't worry about it. Hopefully he knocks it off from now on.