Mighty, Sounds like your dad may think he lost a really good friend when your xh went off to OZ. I can see where he would get depressed. As for the country club...yep, some of them do a lot of social drinking there. I do hope your dad can get back on track for his sake as well as for his wife and family.
Yep, your xh still thinks of the children being right where he left them when he landed in OZ. They don't realize how much time as gone by, nor do they always remember the ages of the children. It's very sad because he's lot so much in the way of life events and spending quality time w/them while they are still young adults. It's something he'll never be able to get back or have a "do over".
You sound good and I hope that things have settled down for you a bit. You've had some rocky rides and you and the children, both, need a smoother road for a while. I hope everything falls into place for your home renovations.
Might, be kind to yourself. Carve out some "me" time and do something special for yourself every once in a while. You need this in order to recharge your batteries.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.