Toni,
I am so sorry for your loss. I lost both of my parents to illness many years ago. As Bob Orme said, knowing their pain was over and that they were at peace helped me. It should be getting a little easier for you with time. As it isn't, I would suggest looking into grief counseling. You may have a minister or other spiritual leader who could advise you. If not, perhaps the American Cancer Society could. If all else fails, ask your mom's doctor or your own doctor for help. You lost a parent, but as a care giver you, in a sense, lost a child too. You have my sincere sympathy.
Pam