Is it wise to be friends with an ex?

We were friends and dorm mates before our brief relationship that lasted only for a month. During that month, it was like he wasn't really there. I wasn't begging to be his top priority over academics and his family, but it was like I wasn't a concern at all. There was no honeymoon phase or whatever that is. I tried to break up with him after two weeks; I was asking where does he want the relationship to go because I don't see it going anywhere if he was like that.

He answered, "I hope this will last." I held on to that statement even if we didn't resolve anything. Three weeks later, he was still the same and I was crying for nights. I gave him a letter asking again what the deal was. He ignored me after that.

Silly me still went on a badminton practice with him and a dormate (girl). But they were closer than when we were together and it hurt a lot. The girl knew we were on a rocky patch. But even when I was crying my heart out on karaoke night in front of them, he didn't do anything and she stayed with him to 'pay the bills'.

I just wanted to save the four years of friendship. I tried to talk to him again but he didn't want to. He texted the same dormate after I stomped all the way to my room and shrieked. He told her I was being immature and that I needed to stop. So, I did.

After a month, he unfriended me on facebook then the texted me good morning the week after; I didn't reply. Then invited me and the same dormate for breakfast, twice. We still don't talk to each other until now. He also distanced himself from our group.

Is it wise to start friendship with him again or at least go back on talking terms? I was wondering if he already did his part on trying to talk to me. It probably is a big effort on his part to text me good morning because he is an introvert. The thing is, I don't really know if I'm completely over him.