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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
In principle, you are traced back to that man because this is confirmed by certainty, and it can only be invalidated by certainty like it. So, if the matter you discovered is merely a matter of doubt, do not take it into consideration because the matter remains on the basic principle that this man is your father, since certainty is not invalidated by doubt. The Prophet, sallallaahu ‘alayhi wa sallam, said: "The child is for the owner of the bed." [Al-Bukhari and Muslim] Subsequently, your marriage is correct because the one who gave you in marriage was your guardian.
However, supposing that you were born out of an illegitimate relationship, there is a considerable opinion of some scholars that if the woman has no husband and the fornicator/adulterer requests that his illegitimate child be traced back to him, he is allowed to do so. This is the opinion of Al-Hasan, Ibn Seereen, Abu Haneefah, and Is-haaq, and it is the chosen opinion of Ibn Taymiyyah and Ibn Al-Qayyim. For further information, see Fatwa 97254. Therefore, that man is your father and your marriage is correct because the one who gave you in marriage is your guardian.
Finally, we advise you to dismiss all doubts, and to be dutiful and kind to your father, particularly that he was the reason for bringing you and your mother into Islam. For further information about dutifulness to one's parents, see Fataawa 82254 and 87019.