My grandfather died of Parkinson's on Christmas several years ago. Oddly, my memory of that is one of joy that he was free. My father is in the end stages of FTD/
ALS in hospice care. We have already lost the person that he was because of the dementia. We are just waiting for the end.
People think it is easier to watch someone who does not know they are dying. I don't know. I just lost a student to cancer---I won't go on.
Combining that with the overwhelming fear of inheritance....
Your dad knew that you loved him and cared for him and kept him home.
I think, although time does not "fix" everything, you will also have this memory. And other, better memories of earlier times will comfort you.
Just know that time will pass. You will start to live again. But be patient. I hope that you will someday find his freedom to be a Christmas blessing.