Delly,
It is such a cruel thing that he had to pass so young, when he should have had many years with his family. You did all you could to help him, but no matter how hard we try, we are only human, and cannot give back health in all cases. What it is within our power to do is to give love and care and companionship: you faced your own fear and distress to do this. Not all people are capable of doing what you did.
It is my hope and belief that your father is in a better place, now, free from pain. As you mourn for him, remember this, and remember that he would want his dear daughter to move back into the light.
Blessed be,
Maria