Such great advice and support -- can't thank you all enough.
Some of the things mentioned are in place. Was already working on the guns -- they are now out of the house and secured at a friend's house.
There is a network of folks currently communicating with him with at high frequency. I spoke with him twice today at length (he did go to work today and functioned pretty well). He says that he is OK. I take his assessment with caution as I know that he is extremely vulnerable to another round similar to last night and he is not accurately assessing his capacity to stay rational and safe (I appreciated the reference to "panic attack" in the comments here -- I think that is a good way to frame his response to when his wife tells him she's done with him). I believe alcohol is now out of the house and his son has taken his prescribed medication (****). I have had resistance from others involved about contacting police -- I know that I can call regardless, and though I agreed not to call now -- I provided the conditions that if they were to occur I wouldn't hesitate. I've advised those closer to his children than me to provide a plan for them if they were to get frightened again by his actions. First, the police, then a nearby friend who would come over immediately.
Re: therapist -- this is an ongoing discussion (he's been in therapy for years). His therapist has been helpful at times, but the fact that she was not someone he wanted to call during this episode or in the aftermath tells me she isn't the right one for him. I told him this but he won't agree to find a new therapist. His psychiatrist in my opinion has committed malpractice (longer story) and I think I did convince him today to get a referral to a new psychiatrist. I'll follow up tomorrow.
Re: MH issues with spouse. First, I agree with the assessment that this relationship is beyond repair and that his best pathway to health is to break from it. Of course you all know that this isn't something he's in alignment with right now -- even though he knows and accepts the basic premises that the relationship is destructive to him, to her, to his and her children -- and that there are no indicators (at present) that things can get better. She is very ill, I get that -- and when she isn't abusing and belittling him, I have compassion for her. I've spoken with my friend over the course of the marriage (about 2 years) about her getting help. She will not. Nothing is about her, everything is his problem, his fault, his mistakes. And the vast majority of her examples are irrational, hyperbole to the absurd, or delusional. She is a brilliant woman and a professional (I won't be specific but she is doctor) -- but she is not getting, and will not seek help.
I am aware that BPD like any personality disorder is brutally difficult to treat -- she's been in destructive relationships throughout her life -- she was mistreated as a child (not just saying this, she's referenced). My friend would do anything for her, but at this point he's got to get past the "addiction" of her and get himself healthy.
FYI: his responses and his kids as well are undoubtedly influenced by the fact that my friend's first wife (their mother) passed about 8 years ago from pancreatic cancer. Kids are home due to Covid -- and are really struggling to handle all of this. They are crazy about their dad, and really scared. It's hard to not be able to take the burden off of them.
All that said -- today is a lot better than last night. Thanks for all of your kind words, your advice and support. Can't tell you how helpful it's been.