This guy would have been a mess, drinking or not. It doesn't sound like he'd be adult relationship material even if he got sober, without tons and tons of therapy--and let's face it, he isn't motivated to do all that work. I'm glad (and I know you are) that you got some great kids out of the deal.
Scary to think about what he'll be like when mom's not around anymore. Maybe he'll wind up like "Billy" from Six Feet Under, sitting around bitching about his life in the old folks' home with his sister (who finally keels over during his last harangue).