I was happy when I thought that one of my childhood bullies had died, but then I was disappointed when I found out that he hadn't
You were disappointed to learn that he didn't die?
It sucks.  I wanted him to die for a while.
It's wrong to act as a bully toward other children, but this was behavior he's probably outgrown, and now probably regrets. It's just as bad for you to wish him harm at this point, even if he mistreated you when you were immature kids. Do you really wish him dead, with all the grief and heartbreak that would inflict on his family?
I still feel mad about what he did to me.
I understand you still feel angry about what he did, but it's time to put it in context and let go. His death won't change the past. You were just kids, and I bet if you talked to him about it now, he would feel embarrassed and ashamed about how he treated you and how it made you feel.