I am so sorry for your loss. You, your mom and all of your family have my deepest sympathy. I truly know how you feel and what you are going through. My husband's situation was much like your dad's. He died 7 weeks after the first indications of anything being wrong and 10 days after his diagnosis of CC. He too was originally given 6 months and was to come home with hospice, but died before that could be arranged. I know this is no consolation, but want you to know you are not alone.
I too had so many questions but agree with Lainy in that all we really know is that we don't have the answers . Hopefully in the future that will change. Seems like it is one step forward and two steps back with this disease.
I take some comfort in the fact that my husband did not suffer too long from this terrible cancer and that at least he is free of this and no longer in pain. I'm hoping you will be able to do the same.
Keep your dad with you in your heart and all the memories of the years you had with him.
Thinking of you and your family and hoping you will all find your way through this sad and trying time.