I see some similarities between our sitches and feel for you. That sht about your son sleeping between W and OP would make my blood boil. Sounds like you have been handling things well and have realized that you can control nothing she does.
I wanted to ask, has your W shown any signs of depression in the past? You spoke about sudden tattoos and changes in behavior, could you expand on the changes you saw in your W behavior wise around the time of BD.
Make sure you are 180ing on all negative behavior and try to become the best version of yourself. I would also highly recommend speaking to a DB coach as it has been crucial in helping me vent and understand certain things.
It sounds like you are currently in LRT, only contacting regarding your son. This is good, keep at it. It was roughly 4-5 months of LRT and me filing for divorce before my W starting reaching out to me again. I want you to understand that your W is not happy right now and will eventually have to look inwards and address her own issues. She may never and will most likely stay unhappy forever. Time and space is so important at your stage as it’s likely your W will realize she is still unhappy and as your are not in the picture anymore she may begin to see that you were not the sole cause of her unhappiness.
Continue to lovingly detach as it sounds you have been. Be strong emotionally and be the lighthouse for her. Watch from a distance. She may reach out and say a lot of things. Try not to focus on the words but to watch her actions. Show her nothing but happiness and kindness, even if you are hurting inside. If she is able to make it through this, and you guys are able to R, she will need to feel forgiveness from you. Don’t tell her that you could forgive her but show her through your actions and stability. Also, work on oozing confidence.
Be kind, but do not be a doormat. Do not bend over backwards for her and be wary of manipulation.
Realize that it is noble to stand for the M if that is what you want. Your old W may resurface if she is able to work through her own issues or she may not. It’s up to you, how long to stand but know that this time is a gift. Time to be the best you, that you can. If things improve with your W, great. If not, you will be a stronger, smarter version of yourself who will be a better dad and a better partner for your next R.