I don't think we need a vet to say that there cannot be a reconciliation with OM present in her life. Otherwise both you and the OM are just backup plans while she enjoys both worlds.
Let's skip mind reading and look at what she wrote specifically.
I have a great deal of sadness and anger about us, our marriage, and the impact of our marriage and separation on our S12.
I have also been feeling an incredible amount of depression and sadness about the way we ended, and the impact of this on S12.
HP, I know you don't believe me, but I have thought of you each and every day and I have grieved tremendously over the pain I have caused both you and our son.
I found her email full of guilt. Guilt that she has broken the family and her trouble in dealing with the associated misery. But nowhere HP is any indication that she feels her actions against you and S12 were wrong. Remorse is missing from her email. No apparent desire to reconcile her actions against what has happened isn't there.
To complicate things even more, I began seeing OM on a very regular basis after you left and have developed a relationship with him.
No indication of an end.
I will understand if you are not interested to talk to me. Whatever happens moving forward, I pray with my entire soul that one day you and I will have a friendship based on our bond with S12.....he is going to give us beautiful grandchildren one of these days and I want to share his life and his future in such a way where you and I can be comfortable and loving with one another.
I have no right to think that you would ever want to remotely talk about us and since I'm certainly in no position to offer you any guarantees ... why would you want to.? I won't reach out to you and bother you about any of this again. take care of yourself.
Reverse psychology at it's finest. She wants you as a friend and her relationship with S12 is troubled. You've denied all that to her over these months. She misses the consistency of your presence while indulging in her OM. The fantasy is breaking down because she needs HP as a part of that equation. She is now facing reality, but still desperately clings to cake eating. That email was a hail mary attempt.
XW. If you end your relationship and all contact with OM, I think you will find me willing to talk about and work on any and all issues -- including my own role in the prior problems we had in our M. But that ball is squarely in your court.
BINGO. Nothing has changed. Don't fall for the cake eating.