Husbandlostatsea,
I’m so sorry you are going through this. I very much endorse BearlyBreathing’s and Sisson’s posts. She cannot continue to work with her AP. Co-worker affairs are notorious for flaring back up. I usually hold that if a WS still works with their AP, the BS should consider the A ongoing.
Like others, I think you may be a little too soon to be in the R forum. You only found out, what, 4 days ago? You are in shock. I’m not saying you can’t or won’t R. But I am going to tell you that you are in for the worst rollercoaster ride of your life, and your emotions are going to be all over the place for a while. It’s ok to hold off on making any decisions until your head has cleared. Like Sisson said, focus on your healing. Think of it like you just got shot. First thing you do is treat the gunshot wound and recuperate.
In the meantime, observe her. What is she actually doing to prove to you she wants to R?
Both of you should be in IC. You, with a betrayal trauma specialist, and her with someone who can help her understand how and why she gave herself permission to cheat.
One of the painful truths of infidelity is that WSs lie. It’s very likely that your WW is still lying to you, or minimizing her A. It’s good that she voluntarily confessed, but you don’t totally know why. You know what she said, but that’s different. It’s possible that they got discovered at work, or by APs wife, and she was getting ahead of it. You don’t really know when it started. I’m agree with the suggestion to DNA test your child. You WW gave birth 18 months ago. She then had maternity leave. The way you relate what she said, it sounds like the A took off right after your kid’s birth? I’m scratching my head on that a little. My suspicion is that, at least the EA part of it started earlier.
Ask her to hand write a timeline of her affair. When it happened, what happened, the key milestones. Any other lines she has crossed with others. Have her read it to you. Consider having her take a polygraph to establish that her disclosure was honest.
Have her write him a no contact letter. Have her show it to you and watch it get sent if it’s an email, or mail it yourself if it’s hard copy.
One thing you should do is find out who AP is and if he’s married. If he is, you need to tell his wife, the other betrayed spouse (OBS). For some reason people fight this, but you need to do it. First, it’s the right thing to do. Second, it’s very likely to kill the A, as he will be scrambling to save his marriage. Don’t skip this step!!