Peace, Your xh is on his own journey and one that you cannot be a part of. I'm sorry for this. If it means he has to move across the country to realize that happiness comes from within, so be it. This may be also the time that he will eventually bottom out...let's just hope and pray he gets himself together.
As for you and your family, continue as you have been doing. If the children inquire about him, be honest and just tell them he's moved and you do not have a forwarding address for him right now. I do believe that at some point, he's going to reach out to the children, but he's not to that point right now. He's got to finish up the replay, etc., before that may happen.
The most important thing is to take care of yourself right now.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.