Sorry to hear you are having such a hard time. My partner and I are 23 as well, but my guy is a pretty mature 23 year old. My only advice is to look out for yourself and your new baby. You don't know if he will turn around and accept his role - you on the other hand, don't have a choice. Are you able to financially provide for yourself and the baby? If so, get out there and start buying baby things - it is so exciting! If not, ask him for the money, without expecting him to be a part of the experience. Is your Dad supportive of you and the pregnancy? The most important thing is that you and your baby have a stable home. Men never really grow up - hopefully, as your pregnancy progresses, he'll realise what he is missing out on, and decide to be a part of it.
I'll pray for you,