Secret baby

My baby’s dad and my cousin are super close buds and I just found out earlier today that my baby’s dad lied about having another child, while I was pregnant he had told me that he could possibly have one but soon after said the chances were slim and he doesn’t even know the other girl. Today I found out from my cousin that he, in fact, has a son in Japan. Conceived while he was based with the Navy in Japan in 2017. I have no clue what to do and I would love it if someone could please talk to me about it. My cousin also told me that he had been staying in touch with the other baby’s mom through email and that he asks for pictures and info while our daughter is in the hospital that’s less then a 10 min drive from his house, he never asks for pictures or updates on how she’s been, while knowing that she was born at 22 weeks gestation and has had multiple complications. Why does he show interest in the baby he just found out about and not our daughter?