I don't have children, so my thoughts might mean nothing to you, and that would be understandable, but I am a data point, and human, so I hope i can add something of value.
I feel that it might be impossible to regret a child, any child, once born, only the circumstances surrounding it. Which of course can create the sensation of regret. All of us are naturally conditioned to love and care for our own or even another's children, at our best, but the conditions of life are another thing entirely.
You have no respect for your OH, this will create an unfathomable weight and sorrow, tarnishing the family connection and possibly disconnecting you from the process of bonding and joy that a new child should create. I'm so sorry you are experiencing this, I would advise some sort of counselling, preferably 'domestic' to hash these feelings out. If the first one doesn't deliver, try again.
I have been there, for other reasons, and it was a terrific help.
There's history here, and we can't make any rash judgements or guesses over the internet, but please have faith. We have this one life, as does your daughter, and we are all the result of our choices; we deserve the power and inclination to accept and make the most of them.
One thing I do know, our society is sick. What is important becomes secondary to the bloody great machine we are caught up in. It takes a good deal of strength and self awareness to hold on, to keep our head's amongst the chaos - money, time, pressure, defeat, loss, pain.
This is so new for you, she is so very young, your world has taken a giant knock. I can only say reserve your energy for the future, without predictions of failure or defeat. Life is short, but it is also long. Have faith, and reach out if you can. I wish I could help, but I am a floundering middle-aged artist who still rents and hugs trees. I had to accept my choices and take charge of my lot. We all do. I wish you the strength to do that, without comparisons or self loathing.
Attack the problem from the root - if this is your OH, there are better on here to advise than I.
All the very best OP. I bet she is beautiful:)