He is acting exactly as an alcoholic would. If you start expecting alcoholic behavior you won't be surprised by his actions.
I second the suggestion of al-anon.
He is your x. He is a grown man. If you interacted with him as such you'd save yourself some stress. For example - not sure why you were at his doctors appt. but think of all the stress you'd have saved yourself had he gone to the doctor like any other grown man - alone. If you could switch your thinking to expect an alcoholic you'd have known right away that you driving was a signal that the date should end before it started. More saved stress and embarrassment. He is selfish. Expect it. No need to go calling around - you know where he is. Passed out somewhere or drinking his way there.
The doctor is a bystander to the wreckage. Not like his words of wisdom (and you don't know what was said in that room) would have turned your xah into a changed man right then and there. You want a depression diagnosis - go to a psychologist. You want addictions treatment - go to an addictions specialist. You want peace for yourself - find al-anon or a counselor.
I've been there and it sucks. One time, after our divorce, xah was supposed to visit the kids. Of course he drives all the way here and decides to stop in at the bar instead. So no visit and sad kids. Then he calls, drunk, and asks if he can come over. Hell no you can't come over. I finally had my little oasis and he wasn't part of it. He shows up at the door, the kids are jumping around......
and I let him in.
I thought I was going to die from all the stress and anxiety before he finally left. What a LESSON I got that night though. Never again. See I had a little space by then. Give yourself a little space and then if you slip up, like I did, it totally hits you in the face because it is more clear. Everything is more clear.