It was difficult for my father when my mother passed away after 37 years of marriage....so losing your spouse after 60 years of marriage, plus the holidays...well they say that time heals....personally I think that time lessens the pain.
You father needs to make his decisions....but should be encouraged to wait for a few months before discontinuing his dialysis. Within that time he may find that he enjoys his children and grandchildren and family, and looks forward to more time with them....such a difficult time...I will continue to keep him in my prayers.