Sleep is good for times like this. There is actually a quote I have from a book I like that explains sleep well.
“Perhaps the greatest faculty our minds possess is the ability to cope with pain. Classic thinking teaches us of the four doors of the mind, which everyone moves through according to their need. First is the door of sleep. Sleep offers us a retreat from the world and all its pain. Sleep marks passing time, giving us distance from the things that have hurt us. When a person is wounded they will often fall unconscious. Similarly, someone who hears traumatic news will often swoon or faint. This the mind’s way of protecting itself from pain by stepping through the first door.” - The Name of the Wind
Keep your focus on your work and enjoy being with the kids. Escape into their imaginations with them perhaps. They have the best imaginations and they can always make you feel better. Kids are great like that, they can turn bad days better.
You can wait or try and get him to talk again. It’s completely up to you. In my personal opinion, I say just let him know when he is ready to talk that you’re there for him but let him know you guys really need to get things straightened out. He doesn’t have to tell you what is wrong with him personally, but you two do need to address the relationship issues but this is just what I think would be a good idea. If the relationship is what is bugging him then let him know he has a certain amount of time (determined by you) to figure out how to tell you because it is too stressful on you.
If you don’t then you take it from there and pick up the pieces but right now focus on trying to make it work. Just try and put the what ifs out of your mind but simultaneously make sure you have a general idea of what you are going to do if things go badly.
I know it isn’t a pleasant position to be in but you are here and you are going to have to figure out how to make it through this. If you feel extremely overwhelmed you could write like you told me to do. It helped a lot and maybe, just maybe, it might help you feel a little better.