At least on this issue, you are morally bankrupt and completely in the wrong. It is pure illogic to think there is any justification at all for extracting child support payments from a man when it is scientifically proven he did not father the child. The fact that a lie was successfully perpetrated for some period of time before a paternity test settled the matter does not alter the correct application of justice. Neither does the fact that the duped "father" and child have established a bond. Fraud is fraud is fraud. If an adult enters into any relationship or takes on any apparent responsibility absent informed consent, they cannot be bound to that relationship or responsibility. It works this way in every other case except current child support laws. Which makes absolutely no sense, especially considering the actual responsible party exists and is known to the party who perpetrated the fraud. Simply forcing the woman to admit the identity of the true father and verifying the fact scientifically provides the remedy for any financial concerns you have about the children.
Emotional concerns are another matter and can never really be addressed by law. It is a personal moral decision each adult needs to make. Certainly, a woman who has lied both to a man and her child/children about who the biological father is has already done serious emotional damage to both the duped man and her own children. That duped man should have the right to decide for himself whether he wants to continue a relationship with those children (if a bond has been established). You cannot force people to love other people.