I am sorry that you seem to be having such a hard time.  I have lost family and friends to lung cancer; none made any great effort to fight after a few weeks but of course I cannot speak for everyone.  I am also sorry that you mother does not feel able to cope but everyone does things their own way.  Forgive me but it may be your father's decision not to fight; lung cancer is a nasty thing and does not often have a good outcome.  I suspect that you are projecting your own worries about yourself onto your father - I bet he doesn't consider you a failure - more of a loving daughter who is walking this difficult road with him.  Have yu considered ringing MacMillan nurses - they have been very helpful in the cases I have known - their Freefone number is 0808 808 00 00 and they can be very helpful, either on the phone or in person.  My best wishes to you.