How did you find the OBP?

Originally I didn’t want to contact AP and just leave everything behind, but unfortunately AP had a child 9 months after her and my husband “just kissed, no way we had s*x at a bar.” This was 6 years ago.

WH has tried to text the AP once and she has not responded. They also hadn’t had contact in 5-6 years. Now I don’t know how to inform the other BP that the child he’s been raising might not actually be his.

I know that there’s a real possibility that this man will never get the autonomy he deserves, but I was wondering if maybe the creative hivemind here has ideas?