LA, everyone has their own experiences and their own foundations. I think the issue is not so much how the first meeting goes, but how you will feel when they make up with him and you hear from them about he and the OW visiting and participating in family plans and how that will make you feel.
Seems like your time is better invested in your own people who will be with you through thick and thin and who don't come with stories and strings from the past.
But, the beauty of free will is that we all get to make our own decisions about these things and I am happy for you with whatever you choose.
