Hi nyazgirl,
I unfortunately have some understanding of what you are going through (you too, georgesgirl) My Dad was diagnosed in May, and passed away on Dec.21st. I at least had on opportunity to spend some real quality time with him, something you were robbed of. I was also very integral in his homecare, something you were maybe spared.
I understand everything you wrote. There are days that I don't think I can face, and even days that I don't. And it's true - sometimes you just can't feel better. But then there are days that you can remember with a smile. Focus on the moments that mean the most. They may also make you cry, and that's OK too. Use your greif as a tool, to remind yourself that life is too short. Leave no words unspoken, and no goal unattempted. We never do know what lies ahead...
You must realize that there was nothing you could do, but the love you obviously have for him was certainly enough to lend some comfort. My Dad said often that the love of his family was sometimes what got him through the day. I'm sure your Dad would've said the same.
Take good care or yourself, and know that greif is part of the process. We're all only human afterall.
Love and Peace to you and your family
Kylie