Reluctant dad

So I gave birth to my baby boy back on 8/31. And ever since we brought him home my boyfriend has been really reluctant to help out. He gets really anxious/annoyed/angry when baby starts crying. He doesn’t know how to soothe him so I end up taking him away because I get angry whenever he starts to raise his voice at our baby. I understand that he’s never been around a newborn and doesn’t know his cues. But that doesn’t mean that I should be the only taking care of him. He’s free to go out as he pleases without even thinking about me or the baby. Sometimes I come out of the nursery and he’s gone and doesn’t even tell me he’s leaving. I need him to be more understanding and know that he has more responsibilities now that he’s a dad. He can’t just come home and sit down or get ready to go out. I’m going back to work full time next week and need him to start helping out more. Before we had baby he was so attentive and would talk about how he couldn’t wait to be a dad. I think the realization of what that entails has finally gotten to him. How do I approach him about bonding more with our son without sounding like a total a**hole? I know myself and I can get very emotional when it comes to serious subjects.

P.S. he helps with diaper changes and feedings. But most times it’s after I ask him to.