I'm so sorry for your loss. My mother died in 2002 from complications of sickle cell anemia. I'll never forget that day. She fought so hard throughout her entire life against that disease. She went through so much, and she was the strongest person I ever knew. Your mother sounds like she was wonderful, strong, and such a fighter especially battling against cancer. All the complications you mentioned...I just couldn't imagine.
That is such an amazing experience. Your mom coming to you and letting you know that you would be okay. What an experience to cherish. I know that feeling that things will not be alright. My mother died when I was 13 and I didn't know what I was going to do. I felt like you do. I asked myself, "What am I without my mother?" The thought of not having her for the rest of my life was almost too much. Like you said...it hurt...and it hurt bad. We can't be perfect. As hard as we try we just can't. For her to come to you the way she did, doesn't seem like she saw you as one who took her for granted. As hard as it can be we must try not to be so hard on ourselves. We have to live our lives, but that doesn't mean that we loved them any less. Like for me, I should have known that my mother was as sick as she was. I should have known that she was moved to the hospice. I should have been there with her everyday that I could have been instead of only finding out everything on the morning that she died. There's so much that we wish we could do because we don't think about them ever not being there. Hindsight can be 20/20. But I don't think they would look at us that way. I don't think they would blame us like we blame ourselves. I think they would just be happy that we did try in whatever way we knew how too. I agree with Kaliope, she answered many of those questions for you. Draw on those moments to give you strength. We'll always remember them, and we'll always keep them in our hearts. I promise you that it will get easier

*hugs*
In a way, I wish I could of had what you speak of. I wish that she or someone in the family would have taken me to side and explained to me what was going on. However, that didn't happen. I must make my peace with that, and I feel that in time you will too. In your own way and time. It's okay to be sad, afraid, and angry if you feel that too. It's okay to grieve. It sounds like she may have tried to have that talk with you, but you just may not have been ready. It hurts that we realize we wanted that only after they're gone, but it does get easier. I promise you that it does get easier.