It sounds as though your husband's heavy drinking is a big part of the problem. If the drinking has increased recently, is he perhaps also depressed as he faces the end of his career and using alcohol to self-medicate? If so, then typically, he is blaming all his unhappiness, with himself and his life, on you. And perhaps the EA is a sort of fantasy, from which he gets a high, and which enables him to escape the real world and, momentarily, his depression. Hence his unwillingness to abandon it, even though he doesn't really seem to want your marriage to end.
My husband had an EA. I see certain similarities between his EA and your husband's. And with hindsight, I feel that depression was at the root of my own husband's actions.
You asked about the difference between your husband's actions now and the PA. I think that the difference is probably the fantasy element. When the PA was discovered, it acted like a cold shower and he emerged very quickly, especially since, from what you say, he may already have been tiring of the Other Woman anyway. His long-distance emotional affair is further from reality. He doesn't have to deal with the OW's physical presence; he can fantasize about perfect love-making; end a difficult conversation whenever he wants by simply putting done his phone...... Basically, at the moment, it's like a Harlequin romance, because fantasy is easier and more enjoyable than reality. And if he's depressed, he probably hates his real-world self and his real-world life and prefers to stay in the fantasy.
He needs to be forced to come back to reality. And to this end, I think you have done very well so far! I think his talk of divorce was the fantasy talking. You'd gone and he felt briefly liberated. He has told himself that you are the cause of all his misery (you aren't, of course!) and you left. So at first he was resentful and lonely. Hence the talk of reconciliation. Then he drank; the fantasy kicked in again and he started to imagine a scenario where he was divorced and probably with OW. I predict that it won't last. Unless the OW seriously wants him for herself and is ready to come across country and grab him. That would complicate things. It might scare him and bring him out of the fantasy very quickly. But it's entirely possible that he would initially be enthusiastic and you'd then have a PA to cope with. (I still think that it wouldn't last, because I think that in his heart he still wants you. He just doesn't like himself.)
If you would prefer reconciliation if possible, then I think you'll need to draw your line in the sand. I'm glad you've made an appointment with an attorney. It will make your husband see that you mean business and might be enough to make him start to emerge from the fog. I hope so. But even if he seems to have come out of the fog, I think that I'd continue with the divorce until you have seen hard evidence of an attempt to change things. In this case, I don't think that simply cutting off the EA will be enough. Because your husband's reluctance to stop, even after discovery indicate that currently, he desperately needs the fantasy. Not, in my opinion, the woman. The fantasy and the escape from reality. That is what he is protecting so fiercely. And if he stays depressed, I think he might re-offend.
It seems to me that if you are to reconcile. he must first face up to his need to deal with the depression and get medical treatment, instead of relying on the alcohol. And to limit his drinking. And if I were in your position, I would make firm and sustained action on that a big part of your line in the sand.
[This message edited by Cally60 at 3:52 PM, April 28th (Monday)]