Hi there.
welcome to the OCF from a fellow Brit,there are a few of us on this site,and along with all the other members i am sure you will find you are not alone with your feelings.
This situation is not something you can cope with alone and my advice would be to contact Macmillan Support.They provide support and counselling for cancer patients,their famiies and survivors.Get proffessional help and try not to be so pessamistic there is always help available and it is not hopeless.
Chin up