Dear DebDaniel,
I am so sorry to hear about your father. In 2000 I went through a similar thing in that my mother and I nursed my father as he was dying...it was extremely stressful and my fibro was the worse I can ever remember. At times I thought I would loose it but then I thought about how my family and mother needed me, my father did to, I was able to get it together. I am not saying you shouldn't feel your pain, you cannot help it. My heart goes out to you so much, the pain is not only in your body but in your heart and spirit.
We nursed my father for 6 months, I know how hard it can be in the later stage of an illness. He was on "hospice care" for the last 2 months.
What got me through was knowing that I was receiving an incredible gift, I was able to give back to my father who had given to me all of my life. I felt that it was sacred to be able to hold my father when he weighed as much as 90 pounds..it was like holding a sweet baby who needed my compassion and love. When my father was healthy I was never able to hold him that way. I feel as if I was given a chance to show my father that he was leaving behind someone who could take care of herself...even if I felt awful I never told him that...I know it is hard but I tried to put myself in his place. In the last 2 months he couldn't talk but I knew he was there and talked to him as if he could hear every word I said. When his time was getting nearer, I kept whispering in his ear that he could let go, Mom would be ok and so would all of his children. I told him that his love and spirit would always be with us, at times I know I saw a smile.
He died peacefully with perhaps 40 of his loved ones around him, at home, in his bed...I know that I was dealing with an angel at the end.

Your father will always be there, I can feel mine with me all the time.
I realize it doesn't make your pain easy, like BLL said, try to breathe, cry when you have to, hold nothing back, it builds up inside and makes your pain worse. It was the biggest loss of my life and you will go through many stages. Don't feel guilty about feeling bad, your body cannot help it and you are grieving.
If you can't sit, try lots and lots of pillows on a chair or on the floor. For me there was another bed in the room so I was able to lay down. One thing I do remember is that my guard never went down and I didn't realize how I was holding my body until after my father passed and I relaxed a little. Try to go into a quiet room or place when you can, breathe and tell your body to let go, at least for a little while.
Remember, this to shall pass, time heals all wounds...try to rest when you can....no words I can say will take away the pain of having a loved one pass away. I never thought I would be able to think about my father without crying, now I think about him and smile
My thoughts and prayers are with you and your family. It isn't easy to loose a person who was your security all your life. Just remember that he is alive in you.
Keep posting, it is important that you let you emotions out--tell us how you are feeling, not matter what.
All my love, Janet