I don't think anyone, least of all me, would claim she is anything other than wrong, wrong, wrong for concealing the fact that it was not biologically his child. But humanity does not fit into units of calculation.
Parents make these awful messes, and it is the children who pay the biggest bill.
wannabe if during IVF I was implanted with eggs that were subsequently proven not to be my own, due to the skulduggery of my partner, and I brought that child up before the lie came out, yes I would carry on doing so, because I would be its mother.