My exH left me for OWW when our daughter was 6 months old. Limerance never ended, they have been married for 6 years.
As a new mother and a betrayed spouse, I wanted that woman no where near my baby. Of course it didn't work. I also did not want my baby alone with her, I think he might have stuck by that.
I did not meet her until AFTER they were married, when my D10 was about 3 or 4 I guess it was. exH had to have surgery and couldn't come down the stairs of his apartment to get her, so I had to do the exchange with her, rather than him. I was far removed enough from the situation to handle it. From there on, she came to my daughter's events, etc. We are now friendly.
I had the "luxury" of my child not understanding why I wouldn't see her for a while. but I knew the day would come where I would have to be able. What I have been able to give my child is the gift of her being comfortable in all of our presences at once. I do it for that reason. I also do it because it was too exhausting for ME to stand on some moral soapbox refusing to meet her because of what she did. It wasn't going to change the situation either way, the damage has been done. I can look her in the eye knowing for myself what she did and she has to look in the mirror everyday. And now that she has gotten to know me, I think it is harder for her, rather than feeling "forgiven" Why? because I was probably made out to be some miserable b!tch by my ex. She sees I am a funny, sweet, thoughtful persona and a great mother. She had has face reality. I bet for all those years it was so much easier not having to stare the reality of what she did in the face.
That being said, perhaps at this stage it is too early for you. But you do have to explain it to your kids. What Rose suggested to say I think is perfect. It will put your son at some ease.
Hang in there. I know you don't want to face the possibility of this affair not petering out. But it is a possibility. But we will cross that bridge if it comes to it.
Right now, DBing your W shouldn't be your priority. Right now DBing for yourself and your kids should be. To manage this situation as it is right now. Right now, she is living with another man has left the marriage. You need to live life in your reality right now.
Sorry Zues, I have too much time on my hands at work. I have brought you back over to the darkside, and I am glad I did because you have a lot to offer.