I could side with a child that had a developed familiar relationship with a duped-non-biological father.
As noted above, in that situation, the biological mother should be automatically stripped of custody and the child given to the involuntarily-adoptive father to raise. The biological mother is clearly unfit, given her adulterous nature, but she can certainly pay child support.
Best of both worlds! Child saved! Loser “mother” pays.
That’s closer to what I’d want than much of the self pitying insights by some Freeper men. Run it up the flagpole, see if anyone salutes! :-)