If the child was born during marriage then the child could be considered yours unless he asks for a paternity action. If it is determined that he is the father then he would be obligated to pay child support and entitled to visitation as the court sees fit. Have you browsed through the information in LawInfo's Free Legal Resource Center to learn more about your issue yet? See:
http://www.lawinfo.com/consumer.html and
http://resources.lawinfo.com/en/index.html. You can certainly try to speak to a lawyer to determine what legal options may be available. In the meantime, you may be able to learn more on your own. Search the "Free Legal Resources" tab, or browse the Consumer Resources. Good luck.