Is it obligatory for a girl to tell a young man the truth after she lied to him about being married in order to get rid of his attachment to her, while fearing that he will not forgive her and that Allah will be angry with her, and knowing that he will not leave her if he finds out she is not married?

You have repented from the relationship, and you must remain steadfast in your repentance. Repent to Allah for the lie that you told. You are not required to tell the man the truth. Do not resume contact with him and sever all ties. Love relationships between young men and women are not sanctioned by Islamic law; they are a gateway to temptation and corruption. The lawful path for someone whose heart is attached to a woman is to propose to her guardian for marriage.