How can I mend what I have ruined and set things right again after marrying my neighbor's wife, with whom I had an adulterous relationship, which led to her divorce from her husband and the dispersal of his family? Is it permissible for me to divorce her to return her to her former husband, or is there another way to repair this damage?

You must promptly repent to Allah for committing a grave sin and a major indecency by engaging in adultery with a married woman. This act is mentioned in the Hadith as one of the greatest sins after polytheism (shirk) and killing a soul. This relationship has corrupted the bond between the spouses, and the Prophet, peace and blessings be upon him, said: "He is not one of us who incites a woman against her husband." The woman also bears a great sin by requesting a divorce without harm, and it is reported: "No woman asks her husband for a divorce without due cause, for she will not even smell the fragrance of Paradise." You are not required to divorce this wife if your marriage to her is valid. If you believe that divorcing her would mend the relationship between the former spouses, this is considered a remote solution. Instead, try to rectify what you have corrupted by showing kindness to the first husband and assisting him financially, for Allah the Almighty says: "Indeed, good deeds do away with evil deeds."