Acceptance sucks.
It's that stuff that you can't change no matter how much you want to, and you just have to own it. Whether or not it should be yours to own.
I went through a really hard period of thinking my whole life was a lie. And to some extent, that's probably true, as he probably never was entirely the person I thought he was. But then it occurred that that was a little bit all or nothing, black and white thinking- too much like a cluster b thinks. Broken down, it was a lot more complicated.
He wasn't actually a bad fit for me in our twenties, and not really in our thirties either. But as life changed, he didn't seem to keep up. As our world got bigger (moving, buying a house, fixing up said house, DD), I think I expanded as a person, and he either stayed the same or even contracted. Things change for one reason or another and it was only as good as the participation of all parties...
You loved her for a reason. It may not have been what you thought it was, even at the time, but that doesn't discredit the life you've lived either
It's so sad for your daughter. Every kid deserves to have that ideal family, though from the boards here, we know that's often not a thing for a lot of us.
Your concern and care for your family is a beautiful thing. It may not be what you wish for them, but they will get what they need because their dad cares enough to do what he can.