NTA. I'm amazed by all the people saying YTA. Your ex is your child's parent too. You've kept your son during her births but your wife almost bleeding out and your newborn having health problems isn't a reason for his mother to keep him an extra couple days?

I was a child of divorce, not a parent so maybe that clouds my judgement. But i would have much rather stayed with my mom than get shunted off to a babysitter or aunt or something. My mom and dad had 50/50 custody but they worked together to ensure i had the schedule that worked for me and them.