Are you two legally married, or living together as a family but not married?
If you're not legally married I still highly recommend you see a family law attorney. You can find out what your rights as a father are, what you could expect regarding custody, child support and visitation and any other legal questions you might have. If money is tight you can get advice from a paralegal. I used a paralegal for my divorce and everything turned out fine. But getting legal advice is very important.