I'm sure others will post with their insightful comments, so excuse me if I'm a bit blunt... .
He's an adult, a grown man. Clearly he made life very difficult for you over many years. You've been separated for a year. I'm assuming you've given him no expectation that you'll return. These are the consequences. In summary, he's an adult, he has consequences.
Any return would have to be conditioned that he gets meaningful therapy, applies it diligently in his perceptions, behaviors and life overall, and demonstrates solid progress over an extended time, probably years. If it hasn't gotten fixed in nearly 4 decades, odds are he will never make the long term effort to make such a major improvement. Accept that. (Acceptance is often listed as the last stage of
Grieving a Relationship Loss. Also
this link)
It is what it is. He really ought to seek counseling or therapy. He may not really listen to you, so if you give such advice it may fall on deaf ears. It's been commented before that the baggage of the past close relationship generally blocks the other person from listening. It is
not your fault. Do what you have to do. Would contacting him in advance about the divorce papers be helpful? Maybe, maybe not. As one example, it might cause him to try to avoid service. Or he might get triggered and start a sour grapes campaign claiming you're the problem, something he may not think of until after he is served if you've not alerted him.
By the way, you'd do well to consider a counselor too, in addition to the peer support here. It doesn't have to be long term but it can help you handle this sort of issue that will arise and catch you off guard.