My husband was also volatile when he was drinking & using drugs. Its good you know to leave when you feel threatened.
I think an intervention is a good idea. But I will say that I would not leave this just to relatives who are in AA and think this might be all he needs is a rehab and induction into that program. I would be leary of an intervention unless you have worked out a proper treatment, and check with insurance issues and all that stuff.
Do research on rehabs in your area, outpatient and inpatient. I suggest looking for one that has a medical component and uses therapy as the core treatment, Look for one that can handle dual diagnosis because some of what your saying could be just alcohol or could be also something more severe mixed in like bipolar.
My husband did poorly when put in inpatient rehab and he was forced to go along with AA program. He ended up leaving and since found help by doing therapy. But inpatient can be good for a person to get some distance and be removed from the presence of alcohol.
You need to live. I love my husband and we are working on our relationship since he is now in therapy and stable. But I couldnt stay if he continued in the crazy, unpredictable, threatening, abusive way that it was for a while.
But there is a lot of help out there, but look for medical professionals first who can help figure out what is going on. He can always end up going to meetings if he chooses but I wouldnt put all my eggs in that basket with the severity of signs like suicidal threats, and previous failed attempts in AA.
Please be careful and know there is hope for him, and for you. But it may be a rough journey. You cant lose yourself and become weak. You will serve yourself, and him the best if you are sure to care for yourself so you can always think rationally, even when he cant.
Its good you do have lots of family support just dont let them snowball things, make sure your insights are heard and respected.