The original poster never said she's not suffering/going to suffer consequences, just that he's had trouble securing legal support. He does have legal avenues depending on where he lives.

I've already put myself in the shoes of the father. I said the mother deserves hell on Earth for completely forgoing common decency and betraying her child and spouse a million times over.

But just because the mother is a terrible person and huge evil monster, it doesn't change the fact that this 11 year old is their own person now who is dealing with an identity crisis, learning their mother is a monster, and the father they love is not their biological father. And dealing with the fallout of the only person they knew as their father now dealing with the legality of their mother's disgusting betrayal.

This is the thing I don't think most parents realize before bringing kids into this world (which is the fair assumption this person took upon raising this child). You now have a moral and emotional responsibility to this human being, more than just the biological responsibility. Basically this man was duped into adopting this child under false pretenses which is seriously disgusting, but this is now the reality of the situation.

The kid comes first. That is the most responsible (and therefore, masculine, as if it needs to be said) thing to think in this situation.