Mary Ann, I feel for you so much. My mother and father divorced after 30 years and even though he was a horrible person, when he died my mother was heart broken.
It was not your fault that he passed away, it most likely would have happened anyway.
I don't know how to heal the pain in you. But trust you made the right decision at the time. You are important and made your decision for reasons and honesty, I think in some cases staying in a bad marriage could have lead you to an early grave.
It is not your fault, you are worth looking after over anyone else x