He’s a danger to you, then he’ll def be a danger to that baby. Cut ties immediately do not put him on the birth certificate, go into the hospital as a no name patient so he doesn’t know when you have your child & raise & love your baby boy the best you can. He doesn’t need to be in his life especially while threatening you while you’re pregnant with his child. Also get a restraining order.
Definitely walk away for your peace and for your children! They don't need to see or hear their mom being disrespected by their father!