I am sending hugs and I hope you can feel the warmth....you are going through a natural process and don't try to fight it...this way you will heal..
if you fight it you won't heal this tragedy. It is a tragedy. Usually one just reads about it and it doesn't happen to you and your family but it did.
I can't imagine a greater source of pain.....I wonder if you believe in the great unknown and can derive some nurturing from the great unknown.
I don't think intellectualizing will help...maybe getting angry might release some of the pain until you move onto the next level of mourning. Maybe you have already gone through a lot of mourning already when you knew your treasure was in so much pain and you were all helpless in the situation no matter what you did.
You were a treasure of a mother to her. Never forget that....She couldn't have anyone better.
Bobby