What is the ruling of Islamic law regarding the marriage of a man to a woman, when it becomes clear to him after the marriage that she had a past with another man, and should he divorce her or forget her past?

If the wife becomes upright and repents, it is advisable to keep her and conceal her [faults], for whoever conceals a Muslim, Allah will conceal him. However, if she persists in her transgression, it is not advisable to remain with her. If she repents, but the husband cannot overcome her past and fears wronging her, he may divorce her.