Treese, So, you don't want to do anything for the holidays? Then don't or do as little as possible. It might be a good time to start some new traditions...go away for the holiday, do something different, etc.
As for your headaches, stress is a large part of the problem and the crying doesn't help either. Yes, you will survive and in time, you'll start to pick yourself up off the floor and start to live again. Right now, it's very, very fresh and the holidays aren't helping.
Sounds like your h is reliving his youth w/a sleep over. Can we say that your h and son are about the same age at this time? Of course it's going to be fun at dad's. He's not the one that has to oversee his son's life right now. You are the parent and you are doing a darn good job of it. Don't allow those fun times to ruin things for you and your son. Chalk it up and go on. It will get old after awhile and your h is going to get tired of putting on that happy face all of the time.
Treese, take care of yourself. It will get better in time, but you have to be the one to take that first tiny step to dig yourself out of that dark, scary hole. You are afraid of what the future holds and for now, look to today and tomorrow and allow the future to take care of itself. One day at a time!
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.