I don't think its fair to have a pop at her feeling sorry for herself, I would never let my Mum in Law spend Christmas alone, me and my husband always make sure that both sides of the family are treated equally. Yes, I would speak to your son and tell him how you feel, why keep it bottled up, don't have to be nasty, maybe even write it down. My DIL is lovely but as most, tends to always choose her family, I completely understand why, that doesn't mean it makes it fair, and I have explained, very nicely, with a bit of cake and me looking after the kids, that I love her as much as I do my son, and the kids are everything, and ever since I have, its been much better. No-one should be alone Christmas. I love my time alone, have spent many years as a single mum, now I have Grandchildren, I want to see them, spoil them, and not miss a moment.