And you keep bringing back the point about you outing him.
Just put it right back into his lap
"You exposed your husband's affair to everyone... aren't you ashamed?"
"I think the person who should be ashamed is the person HAVING the AFFAIR.. dont' YOU?"
Stuff like that is killer
If they bring up the workplace
"The affair is HAPPENING in his workplace. MOST respectable companies have policies against this. His doesn't. I knew nothing would happen to his job. I exposed an indecency in his workplace that he and this woman were creating... That's all... And NOW they are lying to everyone about it... Shame my dear... They aren't any prouder of what they've been doing than I am for having to expose it. I did this to protect a marriage from a predator... No more and no less"
stuff like that is good... mabye a bit more concise than what i have here... but bring the point back ALWAYS that HE is the one having the affair and you won't accept an attack for HIS betrayal.
You can end it with
"You can support a woman attacking a marriage and a family and attack me too if you want, OR you can press this man to END the affair, and save his marriage and home... It's your choice"
"What is best for my kids is best for me"
Persevere = happily being patient over a long period of time