This circumstance should serve as a clue to your friend that he needs to strongly consider getting sober.
I would try writing the guy a letter.
There's no guarantee that it will help matters, but it's worth the try.
I go through life walking a path which doesn't lend itself to this kind of nonsense, but trouble can certainly cross our paths at any time.
I wish him well, most importantly with his sobriety.
Please keep us posted.