All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Dear brother, you have committed a major great sin which is strongly condemned in Islam. Allaah says (which means): {And come not near the unlawful sexual intercourse. Verily it is a fahishah (i.e. anything that transgresses its limits; a great sin) and an evil way (that leads one to Hell) unless Allah forgives him/her.}[17: 32].
As a Muslim it is your responsibility to present the good picture of Islam and Muslims to non-Muslims. A Muslim has to adhere truly to all the teachings of Islam in order to become a good model of his religion, and to arouse the interest of non-Muslims in Islam by his appealing and nice character. Most of them value Islam through the character and behavior of Muslims as the proverb reads "actions speak louder than words".
But the door of repentance is opened wide for every person as long as he does not face the agony of death. So, you have to sincerely repent from this sin immediately. To learn how to repent refer to Fatwa: 81467.
Aborting a fetus even if it is from adultery is not allowed, so you have to advise the woman not to transgress on an innocent life by aborting it as we have mentioned in our Fatwa: 83114.
You have to keep distance from opposite sex in general and from this woman in particular to avoid sinning in the future.
Try your best to convey the message of Islam, and incite her to embrace Islam which is the only true religion. You have to avoid having any direct contact with her. Contact any Islamic center in your area; they will help you in this matter.
However, if she embraces Islam and follows its rulings, then you may marry her, after giving birth, fulfilling all the conditions of a legal marriage. The child of adultery does not have any relation with you. See our Fatwa: 82690.
Allaah knows best.