When I’m not on CC I spend a lot of time on a site for people with dysfunctional inlaw relationships so I’m coming at your issue from that side. It sounds like you and your husband aren’t on the same page right now. It was understandable last year when he had just lost his dad and your MIL had just lost her husband that you would prioritize her visit for Thanksgiving, but that doesn’t mean that that sets the precedent for the rest of her life. I’m a bit surprised to hear that you’ve spend every holiday with your husband’s family… you didn’t ever have a holiday that was just the 3 of you? Would you have wanted that or were you happy enough to have the bigger group even though it wasn’t your extended family? Our family of 5 started doing Christmas just the 5 of us sometimes a few years ago (after usually doing it with my parents since they are in the US or occasionally with hubby’s family) and we discovered that we all really like it that way.
So I have a couple of ideas for you going forward. One is that maybe you and your hubby should consider talking about this issue with the help of a counselor… someone who can be neutral and help your husband understand your concerns. Another thought is that if you enjoy your MIL’s company and want to keep doing Thanksgiving together, what about renting a larger house just for Thanksgiving weekend so you can all be together then? Either in your own city or (in future years) meeting up in another city altogether.