It very likely does not sound as just an affair, it is a replacement.
She had an exit option, once she felt is secured, she became ready to breakup with you.
There is about nothing you can do to save your bond because your WS bonded already with someone else.
She might regret it in the future, but for now it is over.
You should try to focus on yourself, on your future and your child.
She does not sound amicable to you, quite abusive in fact.
Match it and protect your boundaries, don't think it's all your fault: it was the WS decision and you cannot change it.
Do not react either, respond appropriately, amicable if she is, stand your ground if she is not. Protect yourself and your child, that's the only decision you truly have power to take.
If you want a deeper insight about you WS:
She is not a monster. Deep down she is probably suffering through what is happening in a different but similar way as you are.
So way she is treating you so poorly and doubling down?
It's a subconscious mechanism. She feels some level of shame for replacing you with OM and working from an A to a full replacement behind your back for only she know how long.
The only way her nerve system can justify her choices without destroying her ego, is if she can devaluate you to a level so low, that she can tell herself she was fully justified on he choices.
If she can make you the villain, she becomes the hero in her story, and her conscience stays clear.
It is not rational, is emotional, that is why it feels so cruel.
What can you do to preserve yourself during this transition?
This does not mean you can change her direction, but it means your best choice is to hold your frame, do not accept disrespect, do not even argue. Simply stop to be so agreeable. Calmly say no to any of her demands to degrade yourself (live in the basement, to the doghouse... stand up and smile, say 'no way' calm and collected).
If she attacks or insult you, do not react, go along, agree with her absurdities, double down and blow them up of proportions make a joke of it. She says she cannot stand you around? Agree that it will feel so much better once you both will be apart and find your own happiness, with a smile.
Do not pick up on her arguments, she does not want to fix anything, they are a pretext to validate her already set in stone choice. Be functional, not reactive, almost like with a stranger.
For the time you have together, live your life as she has already left, as you were alone with your child. Only interact for the practical things of daily management, do not pick on any provocation she may send your way. Smile it off.
If you have your own interests, working out, meeting people, culture, do it now. Do not hang around her, do not even inform her, start already living your life as she was never there. Your silence will hit her ego more than anything could.
Do it for yourself (for her too) and above all to show your child that no parents should ever push or accept disrespect.
She will still move on, but you will preserve your dignity, and she will always respect that.
[This message edited by BackfromtheStorm at 3:44 PM, Friday, January 9th]