In a sane society, that should be grounds for the man to walk away without any legal obligation.
Tell that to the poor kid that thought he was her father for 14 years.
I'm not defending the disgusting behavior of the mother, but the poor kid doesn't deserve to be dumped at this stage of her life. Being a 14-year old girl is difficult enough without having this to deal with.
Or at least issue an automatic judgement against the fraudulent mother to re-pay the amount of child support extorted when the child turns 18.
The judgement may not be collectable, but if there is now vigorous enforcement of child support, there should be just as vigorous and equal enforcement regarding paternity fraud. However, I am still in favor of the "father" paying support until 18. The child is an innocent bystander in this situation.