Lost,
I am so sorry for your loss. I think this is f&f biggest fear, finding our loved one dead from (whatever). It really doesn't matter what he died from, he had a horrible disease that took hold of him. I am sure at one point he was an awesome guy who you loved completely. That is what you need to remember him by, not what he died from.
Its a horrible disease, it sucks, it ruins lives, marriages, and families. We see it everyday on this form, Take care and do some self care. I am sure he loved you to pieces and didn't want to hurt you in anyway. Hugs that 2020 will bring light and clarity to your life.