Do you really blame him for his actions? It is clear that the guy loves you but you did break up with him because you could not get over your ex. He tried to ghost you to give himself time to heal from being rejected but either his resolve is weak or he has come to a stage where he believe he is over you.

You have hurt him badly before and rightly so he does not want be in the situation ever again. He knows that falling for you again might lead him down the same path where for some reason he is rejected again. Maybe if your ex came back to you, you will break up with him again? No one wants to be in a relationship with a girl where he is considered 2nd choice.

He is protecting his heart from being hurt by you again so give him space. You say he is smart at school. Smart ppl try not to do the same mistake again.