You clearly want a baby so if i were you id keep it. Why not just say to him, you've decided to keep the bub and he can be as involved (or uninvolved) as he wants.
Explain your not going to be asking for child support (unless of course he wants to) and your happy to raise the baby alone (if you are of course).
It sound to me like hes just scared. Who knows once he sees the baby (if he wants to) he may feel different.