Honestly, I could have written this myself, and I've highlighted several passages that I feel apply almost as much to my situation as yours. My dad passed away in August of 2020 and I was absolutely still in shock last Christmas. I'm not in shock now, and I feel l worse in consequence.
A friend has been encouraging me to be a bit festive and to decorate, and thanks to his proddings I'm getting some of it done, and that is helping.
But I guess I've just sort of resolved that this is going to be a difficult holiday, while hoping next year is better.
I wish much peace and love for you and your family, including your cat, who I hope is well.
Jim