Hey, pws, I have been at this for over 3 years. 1 1/2 in the house, almost 21 months out of the house, and 9 of those months with OW. I still have hope and you know that interactions between us have been nonexistent or hostile or friendly in a never ending cycle.
So you see giving up hope is a decision and if you decide to give up that is up to you. I am not to judge anyone else's decisions. But I am trying to reassure you that there may still be hope in your case, too.
take care, I know how hard this is. It sure isn't or the faint of heart.
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.