My babydaddy wants to terminate parental rights for his other child.

I had a baby with my partner and turns out some other girl was pregnant (before me) from a 6mnth split we had. The only way he knew of said pregnancy was through a breakup email with no actual proof of pregnancy and where she said there is possibly another person who could be the dad so he discarded it. (She got outted to have scammed her previous babydad, friends, and family so she wasnt so called trustworthy) Months later, Bam shes in actual labor and he wants to go INCASE it was his kid. She refused. She got wind of me being pregnant and that he was doing right by me and our kid and i guess she got petty and now wants to file for CS. (obviously needs a DNA test to prove its his) It sounds horrible but he doesnt want anything to do with her (The babymomma) and has come to the decision he doesnt want to be involved at all with this child until its old enough to understand the situation because from dating the mom, he saw how she would spend her other childs CS money on herself, and refuses to provide for HER. My question is, if the DNA comes back positive, 1) Does babymom have to sign off on him not wanting parental rights? and 2) If he does, does he still have to pay cs?

i know hes not doing this to get out of paying $$, we agreed that if the baby is his, money would be put aside for it when its old enough to understand the situation, he just doesn't want babymom to be spending it on drugs and alcohol like hes seen her do before.