Hey Starlynn, I'm sorry you're going through this, and glad you felt recognized in what I wrote.
I'm lucky, from the point of view of self-preservation, that I'm not near my ex. There are limits I have no choice but to accept. I don't have to make day to day decisions about how I will respond to his self-destruction (or, his destruction of my life). I don't have to be as strong as you do, right now.
If I were, I'm not sure I'd have the internal resources to try to 'be there', in addition to not going crazy myself. I have a *lot* of support from family. I really, really hope you can find the same for yourself.
I see what's happening to your A, and mine, and all the As out there, as a tragedy. I firmly believe that other people are essential to anyone recovering from anything. The problem is, with yours and mine, you and I don't have credibility with our As as long as we are so directly affected by their lives. Other invested people who care are required, I think.
I agree with most people here that no one can be forced to acknowledge their problem, or to take their own lives seriously enough to try to change things. But, I do think that part of the unravelling of their miserable comfort can start with people who care saying, with as much love as they can manage in pain, that they must.
I don't know how 'interventions' work, apart from what I've seen from the show of that name... do you see some kind of collaboration with his sister and grandmother as possible?