Hi Sally,
So sorry for the journey your Mum, family & you are embarking on.
I personally survived early stage cancer 10yrs ago, but am now waiting on results of tests this week for my Mum, who it seems may have kidney cancer, how far advanced, or if it is actually cancer is yet to be determined. I am a little in shock to be honest, as 7 wks ago Mum was enjoying a holiday overseas, so I can empathise with your feelings.
I think in the early days of diagnosis, whatever stage, the reaction to the news, can be exhausting in itself. The world gets turned upside down. I think the key for your father, you and family is to remember, to take care of yourselves too, eat healthy foods, get enough sleep, that way you can really support your Mum emotionally.
Once you know the extent & prognosis, then you can begin the journey either to recovery or palliative care, to make your time together, special and meaningful.
I don't think there is an easy way to come to terms with the grief associated with an advanced diagnosis, but perhaps it is important to remember each journey with this disease is unique and miracles can happen. At the end of the day though, quality time is important, I think.
Go well and stay strong.
Sam