I'm in exactly the same position as you, unplanned pregnancy and DP can't get on board (but has never asked me to terminate) not that I would anyway.
Like yours, mine is just going through the motions. I attended MW appointments alone although I don't suppose that's out of the ordinary, he will be coming to the scans and obviously the birth.
As I knew from our initial conversation that he "wasn't happy" about the baby I've tried to avoid mentioning it often, purely to spare my own feelings from being reminded that he doesn't "want" the baby that I'm starting to fall in love with myself.
We had a big row a month or so ago when I said we need to talk about this properly, I had began telling friends and family and felt a bit humiliated that he'd respond with dismay when he was congratulated at work or in social settings.
He reassured me that although he doesn't "want" to have another baby right now that won't stop him bonding with and loving them when they arrive. His personal feelings on the matter now won't affect his willingness to be a good father, and that is all I needed to hear to put my mind at rest so to speak.
This will be our second DC and he is a good father to #1.
I know some people get irked on behalf of the men who don't want a baby but are then 'forced' to accept one and be a father regardless of their feelings. The way I see it is he made a conscious decision to have unprotected sex with the mother of his child, and he did so knowing there was a risk of pregnancy. I've noticed that a lot of MN contributors are pro choice (which I respect) but there's also that percentage of us for who abortion isn't an option, and our DP's/DH's have to accept that as sadly for some women having a termination can be extremely emotionally detrimental.
Men do have the option to walk away and not play an active role in the babies life but as you are clear from your post that he is an otherwise brilliant father and good husband, I don't think you have to worry about that.
I have gotten a bit annoyed at my DP at times for being so doom and gloom, it's not as though he has to deal with the physical aspects of pregnancy, the changes it brings to your body or even the sleepless nights (he works nights)
All that can be asked of them is to be supportive, which isn't too much to ask for at all in the grand scheme of things.
OP I hope your husband comes around to the idea, but don't worry if it isn't an immediate turn around.. My bet would be once the baby arrives he will change his tune. It would be very difficult for an otherwise good father to look at a new life he has created and feel nothing! For the moment the baby is not "here" and not all men bond with the pregnancy like we do. I'm sure it'll all work out just fine 
In my case, DP has started to mention the baby more. He'll remind me to eat as I'm "eating for two" (which is a myth BTW) and is making a conscious effort to be mindful, even if he still isn't thrilled about DC2 right now he's still here and he's a godsend with DC1
Good luck with your pregnancy x