Life, may I point something out? You are watching him like a train-wreck. That's where the pain comes from. He is a train-wreck. While he is a train-wreck like that, the D papers aren't likely to wake him up. He knows and hasn't figured out how to stop. He may not know enough to help himself. Yet.
He won't either, until he decides he doesn't like what he's doing enough to change it.
It's not uncommon for relationships to be stronger after major events. Your kids may very well have a much better relationship later and as 25 pointed out, don't have any regrets later. i.e. don't say anything to damage the kids relationship with their father. You'll be glad you bit your tongue and supported the kids and their relationship. No matter what comes of that, it is the best thing for your kids.
Don't be fake, but be honest. If you don't know something, don't guess.
Take the high road and support them. You'll be glad later.
AJ
"Our lives begin to end the day we become silent about things that matter" MLK Put the glass down... "Yesterday I was clever so I wanted to change the world Today I am wise, so I am changing myself."