Honestly, I think the conversation went too long. She crossed your boundary with the OM. Case closed. So are you going to re-enforce the rule about her not being able to have the kids? Do so.
As to the God talk, when she started talking about how God might look at things differently, I would have held up my hand and told her to stop. Then left.
Don't give her the chance to justify anything in her head. Or just laugh at it and walk off. There comes a time when you need to hit her with a truth dart every now and then. My W was the same way in the beginning until I told her to stop talkin' because I wasn't listening any more. Or at least listening to her jibberish.
I would tell her firmly what the "truth" was and left it at that. Calmly, assertively. Made her seem like the crazy one.
Don't ever plead or reason with a crazy person.
I would go ahead and expose the OM to his family ASAP too.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.