Why do you "owe" her anything though? The only person you owe anything to, is to yourself...to do what's best for your own wellbeing.

It's also a red flag that she's trying to keep you emotionally hooked on her, by changing for you. She should only change for herself, not for you or anyone else. Those types of changes, by the way, are only temporary, b/c they are used to manipulate the other person.

Like I already suggested, people can be platonic parents with each other without being involved in a romantic relationship together. It sounds to me, like that is the best alternative for you and your girlfriend.

You can break up with her and still be a platonic friend and loving parent to your child with her, without being her romantic boyfriend. That transition will either be messy or smooth depending on her agreement and commitment to that agenda. If she refuses, suggest a couple's counselor so that you have a mediator to keep the transition smooth for you both, emotionally-speaking.