STBX and I had an ethically non monogamous marriage essentially the entire 10 year run. We are close to the end of a reasonably amicable divorce. My attorney recommended a paternity test for our only child. When I mentioned this casually to my sbtx, she flipped and said that there is a 99.9% chance I am not the father. I’m more distraught about this than any other aspect of the divorce. He is my child in every respect. He is with me as I type this (we have 50/50 custody). I cannot express how much I adore him. While I did not know he wasn’t mine, I feel like my active participation in an open marriage makes me responsible in some way? Should I just proceed as though this weren’t true? As the primary custodial parent, she is due some child support (exact amounts are still being negotiated). Should I just walk away? I cannot fathom it. What are the ethical implications? He is a completely innocent party. My STBX says that if I push this I will never see him again. She says we can push a non disclosure clause in the final agreement but I can think of many reasons why he should eventually know and how will he feel then? What if he finds out sooner and decides to distance himself from me? I’m just spinning and unsure of what to do. Has anyone dealt with this or anything like it? Please be gentle and consider the emotional impact. It might seem simple but there are real lives affected.