Sounds like he's trying to get a rise out of you. Maybe he misses you and is trying to get your attention. Yes, he shouldn't care. De-friending him is a natural move. You do whatever you need to do to get over him.
Maybe he thought you'd still be friends, and took the "de-friending" personally. Well, too bad. He needs to move on as well. De-friending him is not "harsh." You broke up, and don't want to see his status updates and have a constant reminder of him whenever you log on to Facebook. So, he needs to get over it. Don't worry about it. The fact that he wrote you like that is jerky and is proof you shouldn't be with him.
CG-- this is relevant to both this question, and your interests ;)
http://www.youtube.com/watch?v=zUpwmDQ0NQY
Awesome. I also liked this Biz Markie "Unfriend" song...
http://www.youtube.com/watch?v=kI62XFynbIk