First and foremost, if you have definitive proof that he's a danger to himself or others, then by all means intervene. However, it appears there's a fair amount of rationalization on your part over scant information. He's not totally defenseless in all of this...he can stop...he can say no...he can choose to do something different...
Right now I think he's in denial about everything. Like my W, he appears to blame others for his discontent, and the porcelain is finally starting to crack. No one can help him until he holds himself accountable, but there's nothing you can do to facilitate that...his ego is much to strong at the moment to allow it. Sooner rather than later, he'll fall from grace into a pit of despair...
...but that's where you should start pouring some of that PMA you cached away. Keep pouring slowly into that pit until he's buoyed high enough to pull himself out.
I would surmise that's a lot of PMA, so read/re-read the section about depressed spouses in DB and DR, GAL like crazy, and detach. The more you give yourself, the more you'll have to offer to your H.
- Me = 32 y/o - WAW = 32 y/o - M = 2.5 yrs, T = 12.5 yrs - No kids - Bomb, WAW moved out, D filed = 8/15/08