People can survive for many years after a cancer diagnosis, both my father and best friend had about 5 years.
so these treatments (chemo etc.) can extend your life massively. Bluntly speaking its once is spreads that your number might be up.
I think you are maybe in shock, and need to speak to a wider range of specialists, this thread will give you probably more questions than answers- which is great.
I don't know if this is helpful, but last weekend I went to a funeral, and the lady had died from cancer
I am welling up a bit typing this, but she write some words that the priest read out.
she basically said that death was the last taboo, and she had decided to face up to it, and not be so damm scared of it, that's its so very natural. she also said that she had decided to grasp every day, and make the most of it. she did that for many years, and her passing was lovely and peaceful.
OP sending massive hugs and 
don't give up on having treatment, speak to more people, and sending you all my very best XXX
remember 1 week of feeling shit, could give you a year of joy XXXX