Georgie , if you are still reading, or not...
You now know the lay of the land with your dh. You gave an ultimatum over this issue but then did not follow through. That is a green light go for him. He may have a sense of how long to wait between events so as to not push his luck too much.
His disappearing is very worrying and I understand your angst and fears and anger. That is a very big burden for you to carry all the while carrying on with your dc. But then it was all for naught, wasn't it? Next time, imho, you would be right to not care- no anger, angst, worry. His volunteering to disappear is all about him; he is erasing you out of his life for a period of time. Bounce that ball right back at him.
This is something you have chosen to put up with, if you stay. There really is very little gray area here.
Emotionally disconnecting from him is going to be necessary going forward to save your own sanity. You can not control him, you are not his gov'ner. He will spontaneously slip away again. You know it. The only thing you can change is your response to it.
As ill as it sounds he was, he could very well have gone into cardiac arrest; it could have been alcohol poisioning- there was certainly a high level of toxicity in his system regardless of the source. All of this he volunteered for: it is very self-destructive. Going forward, you need to be prepared for the worst financially. Go get a life insurance policy on him today.
Good luck 