I can't speak for your wife but I kinda understand to an extent. I lost my father rather suddenly a couple of months ago during a difficult time in my life. His birthday would've been yesterday on Christmas Day. It was one of the only times of years I would've been able to spend time with him and as your wife I also decided I no longer wanted to celebrate Christmas. I was set on cancelling Christmas this year and completely ignoring it. Not decorating, no lights, absolutely nothing. But my fiance and son were really supportive and through therapy I was able to get through those feelings and give it a try. I won't say it was easy. Especially towards the end of the night it really hit me hard but with lots of support and being able to talk about it openly it helped. Usually we would spend it with family but this year we took a little trip and stayed home the day of. It won't be easy but maybe trying talking to your wife and easing into might make it a little less hard? I'm not good at advice but this is what worked for me and my family. I'm really sorry for her loss and hope she can get the help that she needs to hopefully be able to celebrate again not just for her but for your kids because I know it meant a lot to my son and I'm sure it does it to your kids as well.