I think you need to try to stay close with him but try to give him a little time to think about it and cope with the past relationship. Right now he is afraid to get hurt again and he needs to try to keep some normalcy in his life. Humans are naturally scared of getting hurt and it is even worse depending on your childhood or any events in your life. He needs to be completely sure that you will always be friends and the only way to do that is to keep doing as you are right now and eventually he won;t be as scared and he will take the chance in the relationship.
