You have been through traumatic times before his death and including his deat, and it's normal to have all these thoughts as you process the grief. As much as it hurts, grief is a healthy way to deal with the aftermath.
My mother died many years ago and yet I still have a need to talk to her sometimes, she was a wonderful woman and one of the wisest people I ever knew. When I need to talk to her I take a walk by the water or in the forest and I just let my thoughts flow from my heart to the gentle breeze and on to her. It helps, even after all these years.
You will be okay, keep doing what you are doing and one day it will be just a little bit easier. The pain you feel now will become forgiveness and then the fond memories of better days will remain and the pain of his sickness will disappear.
Hugs