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.
Your question is a bit ambiguous as you did not mention whether or not your marriage was with the consent of your guardian, and whether or not you had witnesses for it at all, or you did not have the elders of your family as witnesses, but you had other people as witnesses. Therefore, in our view, you should orally ask a trustworthy scholar in your country about it. Nonetheless, we will mention a general answer here which will be in the following points:
1- It is an obligation to repent from Zina (fornication or adultery); the conditions of a sincere repentance are mentioned in Fatwa 86527, so please refer to it.
2- The marriage of a person who committed Zina to the woman with whom he has committed Zina before they both repent and before making sure that she is not pregnant from Zina is an issue upon which the jurists differed in opinion. In this regard please refer to Fataawa 83176 and 89292.
3- There are conditions that should be met for a marriage to be valid, and these are discussed in Fatwa 83629. The most important of which are the (consent of the) guardian and the presence of two witnesses. If one of these conditions is not met, the marriage is void. However, if there are children from this marriage, their lineage is traced back to their father due to the doubt [i.e. due to the husband believing that his marriage is valid] as we clarified in Fatwa 92478.
4- The void marriage upon which there is a difference of opinion leads to its effects; if the husband divorces, the divorce takes place. If he divorces his wife three times, his wife becomes irrevocably divorced from him with major separation and she is not lawful for him again unless she marries another man who consummates the marriage with her and then divorces her or dies. In cases where the husband can take back his wife, then Khul’ is considered as one irrevocable divorce with minor separation and the husband cannot take his wife back except with a new contract. For more benefit on the kinds of divorce, please refer to Fatwa 82541.
5- If the three divorces are said at once, the divorce takes place three times according to the view of the majority of the scholars contrary to the view of Ibn Taymiyyah who is of the view that it takes place once. For more benefit, please refer to Fataawa 82330 and 94110.
6- Anger does not prevent divorce from taking place unless the person does not know what he says. For more benefit on the divorce of an angry person, please refer to Fataawa 121374 and 83467.
Finally, we warn against illegitimate affectionate relationships between boys and girls, as they are the source of much corruption and evil.
Allaah Knows best.