I can't control myself, I hate my friend so much?

I found out that a famous guy named Eddsworld was suffering from Leukemia and I told him it was bothering me a lot, and he joked about it. Not in a friendly way either. I don't care if he was trying to be funny or not, it was insensitive and stupid. And if I had the chance, I wish I could hurt him for ever making a joke about Leukemia. I don't care if Edd has a 70% survival rate, but being that insensitive about it knowingly I was already so upset really just makes me wish I could give him a piece of my mind. If Edd actually died, that'd plagued my mind for the rest of my life. God, I hate that kid so much, what should I do/think of this?