Welcome to Whatnext, and best wishes to you and your family.
I think the best way to handle that situation is to remember that different people handle illness and dying in different ways. And that's okay. You are there for her, and do not take anything she says or does personally. If you have a skilled Hospice team, they should also be able to help.
She is suffering physically, mentally, emotionally. You are there to give care and love, and be a helping hand. That's it. Unless she is mentally incapable, she is still the one in charge of her life and health care.
Remember that it's not going to last forever. You do not have to be perfect just do the best you can do. There is one time in someone's life that you can give them end-of-life care, and it is appreciated whether they show or say it or not.
Being both a family member and caregiver can be tough. It's very difficult without knowing or seeing her, what is her mental status, her personality, what she enjoys in life, how she copes with her illness, and so on. The advice I would give is:
1. Give her her own personal space, and personalize it with her. It must be difficult feeling that you don't have a place of your own and you're sort of shifting around.
2. Empower her to control her own life by telling her she can do whatever she wants- or doesn't want, and you're only there to help her if she needs it.
3. Help to focus her mind on right now, and what she can do rather than what she cannot do. Today is all any of us have. We might not have two years, five years, 100 years, but we can try to make today a good day and have the best one we can, with what we have to work with. All people have a 100% terminal condition in life.
4. Get a calendar, and set goals for the near future including things she enjoys, even if it's just a trip around the block or to a park, or watching her favorite program on television. It gives her something to look forward to. If she doesn't want to do it when the time comes, so what.
5. Take care of yourself. Walk away for a few minutes if you have to. Hospice may be able to also provide a little rest for you and your husband to get out of the house for a while.
6. If you need help, ask for it. Hospice is there for you too.
Those are some of the things that come to mind at the moment.
Here's a little booklet from the National Cancer Institute http://www.cancer.gov/cancertopics/coping/when-someone-you-love-has-advanced-cancer/page13