It's so good to hear that, @mystery. This is an awful situation to be in at this time in your life, but it's good to hear that you can see what's happened. I am so sorry that this is happening to you, love. We are here for you if you need us. There are many survivors here who know exactly what you're going through, who have come out the other side stronger and better, who can hold your hand and help you through whatever you plan to do.
I'm very curious, if you don't mind sharing, how long have you been a couple and how long have you known 'D'P? And does he have form for this kind of talk, even just once or twice before?
I get the feeling from the things that he said that he knows exactly what he's doing. I fear that the man you met and fell in love with may be a mask, and that you've just met the real him. Even if he has never spoken to you like that before this incident, this man clearly has the propensity for great violence, not only toward a vulnerable woman who has only just given birth, but also toward a tiny, innocent, and helpless newborn baby. That is utterly reprehensible.
Abuse isn't always a lifetime of constant screaming and punching day in and day out, incessant terror, the inability to escape; it's not what you see in the films. In fact, I'd venture to say that it usually is not like that in most cases. Almost every victim I've ever spoken to says that their abusive partner was lovely when they weren't abusing. Mine was SO bloody lovely and good natured that it took witnessing him trying to fucking murder me before their very eyes for many people to believe me, even with cuts and bruises and scars all over my face and body all the time!
Abuse can be quite subtle, and the effects of emotional and psychological abuse (such as berating you for crying because he has hurt you, isolating you, ensuring you've zero time to yourself, threatening you, going from lovely to monstrous and back, and everything else you told us) can be just as damaging and long lasting as those of physical or "obvious" overt abuse.
You cannot, must not let this go on, for your own sake and for the sake of you tiny innocent baby. You CAN cope on your own, and you will do just fine - likely even better that you imagine. I know you think you can't, and it IS absolutely bloody terrifying, but there is plenty of help and support out there for women in our situations, and one day you will look back and thank yourself for getting out.
The best bit of advice I can give you is keep the thoughts of leaving close to your chest. Do not let on to him that anything is amiss, because if he finds out that you have plans to leave, it's possible he could become even more dangerous. Ring Women's Aid, a solicitor, your family, and whoever else you can while he is out of the house; don't even do it when he's in the other room and you think he can't hear! Keep your plans to yourself, go on as normal the best you can, and conduct all activities while he's out.
Look after yourself, love, and remember, we are here if ever you need us. 