I think most of us have been treated badly by someone we care for with cancer.   It's the old saying you treat those closest to you the worst.  It's mainly frustration on their part.  This is how I have coped, walk away from them and go to a different room, arguing makes it worse.   Secondly tell them the truth about their actions and remind them they need you so being horrible is not an option.   Just because they have cancer doesn't give them the right to treat you badly, it makes them stop and think.  Hopefully this will help you a little.   Carol