He could have a lot of anxiety since the baby, and it is making it worse. Marriage counseling for you both and anger management for him might help if he is willing to. If he isn't willing, then you need to decide if you still want to be in this relationship. You also need to ask yourself if you want your LO growing up in an environment like that.
One of my friends parents was like this. Everytime the husband would say name to her, she would simply walk away. Mid sentence as he said it too.
That’s definitely a narcissistic tendency. It doesn’t sound like he’s a full narc, but he shouldn’t be treating you like that regardless - and especially when you’ve already spoken to him about this specifically. Threats of divorce during a fight is a coercive control tactic - it’s like a test to see how committed we are. I’m sorry mama. Talk to him about it again and if it doesn’t stick this time, he’s just not respecting you and you deserve better than that. I’m sorry you’re going through this. I’ve dealt with this too. It’s exhausting