He admitted the baby wasn't his.

Me and my ex have been going through a tough paternity/ custody battle. He doesn't care about the baby, his parents do. I do not like his parents. They harassed me at the hospital when I had my baby, then continued to harass me when I got home, until my mom stepped in and told them to stop. My ex did the worst thing possible to me. Less than an hour after my emergency c section, he told me he was demanding a paternity test, in the rudest way ever. Telling my parents "the baby doesn't look like me, she's a fucking liar."  He took place over my dad in the operation room. I could've had someone in there who loved me and cared about me who wanted to be there truly but he was. Then after he hits me with that. My mom almost punched him. My dad then told him to leave. My ex has the nerve to stop my nurse and tell her he wanted a paternity against the bitch in room 107. I was horrified. My baby in the NICU, I'm drugged up not even sure what's going on and just heart broken. 2 months later today, he still hasn't owned up. He called me today saying "that kid isn't mine, she doesn't look like me, I want to sign my rights over." I was happy. This could all end, all my stress and depression. But I didn't record it. I have no evidence he said that. It was over the phone. Is there anyway I can get it to use in court? His parents have been using him as a puppet. He doesn't care about the baby, but they do. But they disrespect me, they call me names, threaten me, harass me etc. I feel like they want their hands on my baby for the wrong reason, so they can hurt me. So they tell him that he should fight for shared custody, pay his legal bills etc, and he lies saying he wants the baby and he wants to be apart of her life, when in reality his parents want it all. Him saying this today could've helped me, because he has been lying in every legal event, telling the lawyer he wants to see her when he truly does not. They all have bad intentions. What do I do? Is there a way I can access this phone call?