Hi,
I'm so sorry you had to go through so much with your Mom's illness and that you're stiil having a hard time. Even though your description was graphic, one thing was obvious - that you were THERE for her. That is something to be very proud of and you were a good daughter. Thank God she wasn't alone. Grief is difficult and different for every person. I hope in time, that good memories will slip in , to replace those bad hospital memories.
I remember my mom who died 15 yrs ago after a long battle with strokes. In the final days I remember being with her all the time. I remembered laying my head on her chest and thanking her for being such a great Mom.
You said your problems started when she got sick. I'm sure your Mom wouldn't want you to feel bad at all. She gave life to you and wouldn't want you to spend it feeling sad.
I hope the waves of grief will give way to peace and fond memories. Try not to think about the sickness and the horrible death, but instead think of the great qualities that your Mom had.