Mary,
Cancer, and all illnesses can be very depressing and life altering. I have gone through two battles with thyroid cancer in the last year. Each time, because of the treatment and preparing for the treatment, I changed as a person. I became depressed, cranky, and somewhat impatient with people. The key was that I kept looking for the light at the end of the tunnel. Sometimes I would loose that light and friends, family (spiritual and physical) would remind me to keep going. Most of all they didn't put up with my failing. While they didn't berate me about it they also insisted that I not let it rule me.
So, my advice is love your husband. Even when he does not want to be loved. Reach out to him. Show up at the hospital each day. Bring him thing that he would enjoy -- food, flowers, videos. Find things to do that are fun and enjoyable. Read a humorous book together. Read from whatever religious texts are the foundation of your faith together. Most of all don't let him slide into and become comfortable with his anger and depression. In a loving way coax him out of it and resist his tendency to fall into self-defeat.
Know most of all that there are powers out there greater than we can ever imagine and our faith in those powers can be greater than our weaknesses as humans.
God Bless,
Marlin