What is the ruling of Islamic law regarding my continued marriage to my wife who had an affair with another man and then repented, knowing that I had previously wronged her by engaging in illicit relationships?

If your wife repents sincerely for what has passed, then keep her and live with her kindly, for repentance erases what came before it, and one who repents from sin is like one who has no sin. Be keen on steadfastness in repentance and righteousness, cooperate with her in obedience to Allah, and guard the limits of Allah so He may guard you in yourself and your family. And the Messenger of Allah, peace and blessings be upon him, said: "Be chaste regarding the women of others, and your own women will be chaste..."