I guess I would go meet her with the mindset that she is just bringing you mail but have a tenative plan in case it is something else.
My friend who D her H several years ago, told me that she didn't realize how much she loved her H until she discovered he was dating...my friend was engaged to be married. She immediately broke off her engagement and went to H to tell him that she wanted to work on reconciling. They remarried and have been married for two years this time. My friend said that there marriage is now better than it ever was in the past.
I am not trying to give you false hope but be prepared that you dating has jarred her into reality.
Good luck and keep us posted.
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.