It's amazing how the issues with S are no different today then the very first day you went on this board. M commitment is simply a different animal.
I think Michele gave you a great reply. I may quibble with the precise meaning of her definition of "joy"--but the essence of her message is that you have to set the path on your own and S is free to join you on his own or not. It seems the only times S has truly responded to you on a critical decision is when you set the path--either when you first went LRT on him or when you decided to have this baby. I suspect if you called the whole relationship off and indicated you would seek a court order of support--he'd get a real does of reality and start making some decisions (I'm not urging this course, but only use it for illustrative purposes).
And Jennifer, please don't take the following as a rap against you, I am far from the person who should cast judgment on others and I hope the folloing is not viewed as such. But on a simply human level, your sitch exemplifies to me where straying from traditional values on relationships, sex, and its consequences can create so much havoc that extends beyond our own lives and impacts others. I say this only as a warning to others on the BB seeking comfort in other R's where our S's have rejected us. I already know of one unwanted pregancy that was ended and would hate to hear more.
That being said, Jennifer, I'm really, really proud of you for keeping this baby. But I agree with Michele that while you can envision the best scenario for that child (a committed M couple), that vision may be illusory and potentially destructive if you try to force it by your own sheer will. I've learned as much in my own M with an outcome I did not desire and I don't want the same thing to happen to you. There is peace at hand if you choose it. Good luck.