Alright, I figured this out a little while ago. If not, sounds like a plausible story.
Father cheated on girlfriend (OP) and the girl in question got pregnant. OP is pissed off about it (with merit) and father and op need a way to make this better so her 2 kids don't get slighted. Father and OP decide (apparently getting mother to go along with this
) to let father throw away his kid and become the neighbor next door or the mailman or the ice cream man or the man at the grocery store. Now, he's such an upstanding individual that he will throw away his kid, but he will absolutely send a small stipend to mother for "support." Not child support, because he doesn't intend on this being his child... just "support."
I vote for adoption. Give this child to SANE parents.
OP... just let prince charming know that no matter how "complicated" this situation is, he will need to be able to explain it (in detail) to a judge so that the judge can hear it, then (hopefully) deny his request for a TPR. No one, (IMO) has considered the best interests of the child in all of this... everyone involved seems to be considering the best interests of the adults, or maybe where you are concerned, the best interests of YOUR children.