Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
We congratulate you on your repentance and present you the great good news that is granted to those who make sincere repentance. Allah Says (interpretation of meaning): {And He it is Who accepts repentance from His slaves, and forgives sins, and He knows what you do. }[42:25].
As for the woman who is threatening you of uncovering you or spreading your sin, that is forbidden and by doing so she will commit a great sin. Remind her that if she covers your sin Allah will cover hers on the Day of Judgment. The Prophet (Sallallahu Alaihi wa Sallam) said: "Whoever covers a Muslim Allah will cover him on the Day of Judgement". If she accepts your advice then Praise Allah; otherwise, trust in Allah, ask His help and do not stay imprisoned by this fear but you should defend yourself.
Also, you may use indirect or illusive expressions that indicate you were not involved in any such crime. This is the same style Umm Sulaim used with her husband when her son died. When her husband, Abu Talha, asked about his sick son, she said, 'He is more tranquil than he used to be, and I hope that he has taken the complete rest'. He understood that she meant his health was better while she actually meant his death.