Everyone telling you to suck it up is a terrible person. They shouldn't be listened to and, in my opinion, are terrible parents. Sure, you knew the risks, but I know the risks when I crossed the street and if I get hit by a car and have to spend the next 18 years miserable and paying huge bills I have every right to be bitter.

Leave her and leave the child. This is an irreconcilable difference and the power was in her hands. Her body her right, sure, but she doesn't have the right to control your feelings. Your daughter deserves to be raised in an environment that is not dominated by this toxic interaction between you and your girlfriend. It won't be long before your daughter is old enough to start picking up on it. She leave now she'll never even remember you and that's probably the best for both of you. You didn't sign up for this, you both were clearly and explicitly taking measures to avoid pregnancy. She changed her mind and made the choice, while your only choice was engaging in a basic human need whilst doing everything possible to avoid pregnancy.