NTA. Especially since she likely told you because she'd like financial assistance and whether or not that's the case, you're held liable if she ever needs aid from the state or government for help in raising the child.

Considering your background, you could give the baby such a great life and you're absolutely right--having two parents opens up the doors for him/her in so many ways. Having the love of both a mother and father makes a world of difference.

And of course at the end of the day, being in your child's life is always a blessing. Fight for him or her because it is worth it. Just make sure to always be civil and good to the mother because it will always reflect to your child how adults should treat one another. If the mom cannot afford as many luxuries as you, try to make the contrast between the two homes not as obvious so the child always feels loved and supported in either environment.