The expose the affair to the workplace is a huge action Mel.
You have to gauge your marriage and where its at NOW vs where this action may put it later on...
My impression now is that OW isn't letting up and your husband is leaning towards divorce...
You could check with a lawyer first to find out your options if your H is unemployed and he files... your call...
But if they are both out of work that's going to take the excitement and fizzle out of the affair for sure... Affairs dont' die out quickly, they take several well executed hits to the head before there's no life at all left in them
This would be one of those well executed hits to the head
Begging and reasoning don't make a dent, ACTIONS like this DO
You do'nt warn him either.. if he isn't cooperating with you and you have a verbal confirmation from antoehr cooworker who will back you up if HR wants that then I say do it