Hi M.,
I can kind of relate. I'm not always thrilled to see more days that involve more work for me while feeling depressed that things don't ever seem to work out the way I plan. So, although we get there different ways, I think we feel about the same way. I'm working on adjusting my attitude, maybe it will work for you, too.
Try volunteering during the Christmases that your son isn't with you. It certainly gives you a chance to see your blessings in a whole new way. When I have to go to my in-laws, I try to make myself listen as a way to get to know more about my husband rather than getting aggrivated by having to listen to stories I know nothing about. Also, is there any way you and your husband can come up with to make the visits with your in-laws more fun? There is a game we've played at my family's Christmas parties for years. It has many names, depending on who you talk to, but it works like this.
There has to be at least one NICE gift, a few pretty good gifts and a few "fun" gifts to make it the most fun. It can be done a number of different ways. Maybe 1)everyone would take turns buying the different gift levels or 2)everyone make a donation and one person does the shopping or 3)you and your husband do all of the shopping as your gifts to his family.
Then, one person (that could be you) keeps track of who got what and who stole it. (No gift can be stolen more than 2 times. My mom would take a pad of paper and make 3 columns and do it that way.) To make sure that the "stealing" get started, because no one ever wants to go first, my parents always gave me a low number (3, 4 or 5) and I'd steal the best gift available at the time, knowing it could still be stolen again -- and would be.
Each person draws a number. The person with number picks a gift. The person with number 2 can either pick a new gift to unwrap or steal number 1's gift, and so on. If your gift is stolen, you get to unwrap another gift or steal from someone else, but you can't take back the gift that was just taken from you. My mother would always pick one "fun gift" (like a box of envelopes) and after the game was over, she would tell the person that in the front (or back)envelope, there was another gift (maybe $20, maybe tickets to a ball game) something really good to make a yucky gift suddenly a much better gift. Everyone leaves with something, its a lot of fun and takes up a fair amount of time.
The first year, people are a little shy about stealing, but never after that!!
Good luck and I hope your holidays are filled with much joy!