My heartfelt condolences to get to know from my friends of the death of your father. I understand very well that this would be a terrible tragedy for you and your mother, as he was critical of both.
But it does not help when the dead can come to anyone at any time. No one can prevent its occurrence. I know that you return gratitude, all time ago.
I send my deepest sympathy. I hope it may be of little comfort to you to know that your friend still miss you and are willing to share your grief.
With best wishes to you and your mother.