It is great that you are excited. His attitude probably will not change. That isn't what you want to hear, I know, but it probably wont. Or he will be one of the guys, who after you support and raise the baby on your own for the first six or eight years, then they will come around and be all buddy buddy to the kid. Ya know, superdad! Grrrr. Men.
Anyway, you can do it on your own, dear. You sound mature enough to make it. If he really thinks that this is "ruining your lives" then he should have thought about that before you two had sex.
Just make it known (which I am sure that you have) that you want him to be part of the baby's life and that he is welcome to see the baby when he wants and just go from there. Maybe he will change his mind once the baby is here, but just don't get your hopes up, that's all.
Good luck to you and congratulations!