I’m very sorry for the loss of your baby. These things are difficult for the fathers as well as the mothers. It makes sense that he might be all over the map, emotionally, after the death of his child. Since I don’t know much about you or your relationship (ages, how long you’ve been together, broken up, what the relationship was like, etc.), my advice is to at least sit down and have coffee with your ex. Processing the death of a child is important and tough and whether you get back together or simply talk over a drink, the connection is important. I don’t think you have a lot to lose if you keep your expectations low and your heart open.