Well, after a break up, it's really common to have mixed feelings and complex emotions. You can't just shut off that he once was close enough to you that you married him. You can even have fond feelings for him still and not have it mean you should be together. Is there any way you can talk to a counselor and work through some of these emotions you are having?
How did he take the divorce? How is he feeling? Is friendship an option?
I don't want to pry too much but how did you two even get married if you got fed up with it only 4 months after. I don't think that "oh I stopped loving him" is an answer here, you don't stop loving someone just like that so you probably never loved him to begin with.
I can understand why he would be upset. Serving someone divorce papers without even preparing them for what's coming, or talking to them about how your relationship is failing is cold-heated and plain selfish. Could have at least given him a heads up.
I assume he is actually hurt after this and he needs his space. Don't pursue friendship after this cause you just might give him false hope, give him some room and focus on yourself.