I married a woman and discovered after the marriage that she had a previous sexual relationship, and I am thinking of divorcing her because I am unable to continue with her. I ask about the ruling on divorce in this case.

All praise is due to Allah. You erred by pressing your wife until she told you about the haram act she committed, and it was incumbent upon her to conceal herself. If she is repentant and no suspicion arises from her, then you should keep her and not divorce her, because repentance erases what came before it. However, if you cannot bear to stay with her, there is no sin in divorcing her. And Allah knows best.