I really don't have any suggestions. I wish I did. I just wondered if you thought there was something you could do different that would cause a change in him. Who will be helping you out after the surgery? I had the same surgery about about 8 or 9 years ago. Take care of yourself. I am telling you that you will not believe how much better you will feel after you recover. I went from having one good week a month to feeling good all month.
Everything happens for a reason, maybe Dad needs to find that it isn't better out there, he needs to realize how good he had it here. Maybe he will find God and that is the most important thing when he finds Him he will know he is supposed to come home.