I'm going to decide to move on from one of my closest friends
What exactly does this move mean to you and how will you do it?
It means I'm going to start to hang out less with him and then finally later dump him
Outgrowing a friendship is what you have done, it is inevitable. Your friend will be hurt, and that is his right, but try to not be so cold about it. Perhaps explain to him why you want to move on, and then he won't have any confusion as to what he did to deserve such treatment from you.
You are only saying that because you stink at maintaining friendships. I'm just not interested in hanging out with him anymore. Nothing cold about it.
Well, just saying that he might want to know why is all. No need to insult me, I thought you were a better person than that. I feel like some people just need to chill and not be so rude to others.