Marie, don't be friends with him. He needs to hit rock bottom but he'll be back. It could be a few months or a year (just look at success stories in piecing or reconciliation)but I bet closer to a few months- especially since this woman is random- not a close friend or coworker!.
There will be nothing you can say or do to help him. Well- if you just move on and avoid him while he self destructs, it will help him end the affair sooner! If he is an alcoholic, have you seen any signs before this?
me,34 exH,34 S,16 months S:3/31/09-left for OW started DBing 10/09 d final: sometime 10/10 current: http://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2022856&page=1 met in 2004