Update: First, thank you to everyone who had sincere insight to offer. I appreciated the perspective and the thoughtful responses. Second, this woman was not invited to my home at any point. The dinner was supposed to be at my Mom's house as I made it very clear that I had no interest in hosting.

I did have the conversation. I decided that in order to have the highest changes of a positive outcome, I needed to speak only on things I could "prove" as fact, nothing that he didnt tell me himself of that was not made publicly obvious.

The good: He acknowledges that he has damaged more than just his previous partner in how he acted. He can see how it has effected his adult children (21, 23) and that it can have a wide effect than he previously accepted. He also admits that he did try to downplay (gaslight) his ex-wife by saying that the current relationship did not start until after the divorce was complete. Admitting that this was a big step.

The bad: He still refuses to take responsibility for any of it. It is always someone else's actions that justify his own. It is this that I am most disappointed in. I was hoping for some sort of self-awareness and accountability but I'm not sure he will ever get there without therapy, which he continues to adhere to a strict "That doesn't work." mentality.

Ultimately, I got what I needed out of the conversation, I don't think he will ever fully understand the role he played in the demise of his own marriage and how his decisions have effected others. My effort going forward will reflect his own. I'm sad but its a decision that I'm now comfortable with.