Well, he's continuing to show how he's always been--behaving in his own best interests regardless of how it affects you. he doesn't care that you will live an unhappy life as long as he gets what he wants.
It's not selfish to have your big heart redirected to yourself. Many women are nurturers by nature, but when you're not nurturing yourself, that's really sad. You have to have your own back for your own precious life on this planet, because really, you can't always count on others to do what you should be doing yourself.
He doesn't know it, but you will be doing him a favor by freeing him to perhaps find a woman who will truly love him and be happy with him. But regardless of how his life turns out, he's an adult and will figure it out. He will no longer be your concern, besides wishing him well as the father of your child.
In your shoes, I'd not say anything for the time being while removing him as an approved user of your credit cards, bank accounts, etc. Remove him as a beneficiary in any of your accounts. Consult with a legal representative. And then draw up the legal paperwork, presenting it, and have a spine that you will not be changing your mind, while reminding him it's in your daughter's best interest to keep a pleasant environment for her. That from now on, co-parenting will be the only discussion you will have, besides hashing out legalities.
Do you have extended family in the area for support? I don't suggest leaving the home, as that might negatively impact you, which you can ask the legal rep about. But you might make yourself scarce more often, so that you can lessen your time around him until separate lodging can happen.
Breakups are upsetting for everyone, so there is no way of getting around that. But now you will have a chance to build the next chapter of your life any way you choose. Don't let anybody get in the way of you doing that. Read some books on building your self-love, since being a sacrificial lamb to your own detriment is not healthy and abusing yourself. Good luck and let us know how it goes.
P.S. I'm speaking as someone who has experienced something similar, and began divorce proceedings when I was close to your age.