I am so sorry for your loss but you must stop feeling guilty. Through your years together and the way you took care of him I know he knew how much you loved him. I went through a similar situation with my husband of 66 years I joined a grief program through my church and it really helped. I learned to take one hour at a time, one day at a time, don’t worry about yesterday it is gone and tomorrow will take care of itself only think about today, get out for a walk if you can.change your daily routine to a new one. Hopefully your family and friends are taking you out for coffee, go do not stay home.Dwell on the good times you shared. Let the love you shared over rules any other feelings you have .