Hello,
My deepest sympathies to you on the passing of your mother. I too lost my beautiful mother earlier this year, to PC. She was 83. I know some of the pain and sorrow you must feel.
My mother's passing was very quick as well, we too, did not know that what was going on inside until things were at a very advanced stage which is, unfortunately, very typical of this disease. The experience was very surreal and things happened fast, despite all of our efforts to find solutions and make my mother as comfortable as possible.
My consolation is this, that our loved ones are in a place of peace and comfort, and surrounded and cared for by those who have gone before. This is what I keep with me. We lost my father in 1988 to colon cancer. Sometime before he passed, he said that he saw Jesus, something that gave us all a lot of comfort, and relieved our fears somewhat.
I am glad that you were able to spend some time with your Mother, and to tell her that you loved her. Like you, I was not there when my Mother passed, but I've often wondered if this was for the best. It would have been so very hard not to fall to pieces in her presence. I am so grateful for the opportunity that I had days before, to tell her how much I loved her.
I picked up a book entitled, 'On Grief and Grieving', by Elizabeth-Kubler Ross who wrote on Death and Dying. It has been very helpful.
I wish you much peace and strength in the coming days. God bless.