It sounds like your h was missing the family unit and what you did as a family, i.e., tree decorating. Sure, he was disappointed that your son didn't want to help him decorate earlier in the week...but this is something he's going to have to face as your son continues to grow up w/o his father being in his life full time. Some of the consequences of his actions are biting at his heels this year.
I know you want to feel sorry for him...but don't. He made the decision to move out. Your h could have remained home, sought counseling and worked on his issues...but he didn't. Tomorrow, he'll back to his usual self because he got the attention he wants, i.e., son coming over and helping him trim the tree.
You will see a lot of this "poor me" during his crisis...don't buy into it, especially during the holidays. They feel the tugs of their old life and miss the things they did w/their family...but that will soon pass when the holidays are over and done with.
Continue as you have been...like a teenager, he'll get over it or he'll trim the tree w/or wo your son's help.
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.
