Next time I'd stop him in mid-shout/abuse and calmly tell him to leave your office and not come back until he has a civil tongue in his head and make him do it; just interrupt anything he might be insisting on/saying/etc. if he isn't pleasant enough. He has gotten away with his behavior for 38 years, no one standing up to him, it doesn't matter if the boss or his friends, neighbors, or countrymen don't stand up to him, you should for your own sanity?