Is it possible that the Prozac is causing some of the anger? Wasn't there some concern about people on Prozac several years ago? I was on Prozac for several years for depression until it quit working and I started down that long dark tunnel again. Since I am on another med, I feel much better. I feel more centered than with Prozac. I don't think I had severe mood swings but I did seem not to be as centered as I am now.
Hope you find a solution, my heart goes out to you. There is nothing worse than suspecting your child has a problem that you cannot just make go away for any parent. I would imagine being a doctor would cause more anxiety during a time like this. We humans expect too much from ourselves at time. Don't forget to take care of Elle, too.
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.