All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
This man is still a non-Muslim. So, Islam forbids you to marry him until he becomes a true Muslim; i.e., not just pronouncing the Shahaadah (The Two Testimonies of Faith) in order to marry a Muslim girl.
Now, even if he becomes a true Muslim, you are not allowed according to the Sharee’ah to get married to him without the consent of your guardian (father if alive or closest mature male relative from the paternal side). The Prophet said: “Any woman who gets married without the consent of her guardian, her marriage is invalid, her marriage is invalid, her marriage is invalid.” [Abu Daawood, At-Tirmithi, and Ibn Maajah]
The Prophet also said: “No marriage can take place without the presence of a guardian and two reliable male witnesses and any marriage that was not done in this way is nil and invalid.”
Anyway, you should fear Allah and sever all relations with this man immediately and indeed with all other non-Mahram men. In fact, establishing illicit relations with men is forbidden and it leads to being dragged to the swamps of depravity and dissoluteness. In fact, you lose by this kind of relationship your honor and become regarded by righteous and pious men as a non-desirable person. So, fear Allah and wait for a righteous and pious man with whom you will live a life full of joy and satisfaction and get righteous and pious children, Allah wiling.
Allah knows best.