My last partner (not an alcoholic) had many narcissistic traits. I tend to doubt he would be diagnosed as NPD, but he was, I think, on the spectrum.
I remember he once threatened to disclose something private to my office, after we had separated, unless I did something he wanted me to do. I called his bluff and said, "Go right ahead, be my guest--and I will be filing harassment charges so fast your head will spin." Never heard another word about it, and needless to say, it was all hot air. He was very big on saying how he was going to do this or that to someone who had angered him, but he never followed through even with reasonable actions he could have taken against them.
I know you have a pretty good handle on what you're dealing with, For--my comment/caution was more for the newer folks who are still trying to figure out WHAT it is so they can FIX it. (One more tip for newer folks--even if you figure out what someone else's "issue" is, you can't fix another person.)