How can a girl who has repented from repeated adultery with a man who broke his promise to marry her, make a sincere repentance while keeping the matter a secret, and does the man bear part of the sin?

The girl must offer sincere repentance and cut off her relationship with this young man, as part of her repentance for the sin of adultery she committed. She must also conceal this matter and not inform anyone about it. As for the man, he is sinful for deceiving her and inviting her to adultery, along with her own sin.