Adultery in Jewish Law

Greetings and blessings. The Torah is very strict regarding a husband who is unfaithful to his wife and engages in relations outside the marriage. As implied by the verses of the prophet Malachi chapter 2 verse 13: "And this second thing you do: covering the altar of Hashem with weeping and groaning, so that there is no acceptance of offering from your hand. And you say, `Why?' Because Hashem witnesses between you and the wife of your youth, against whom you have dealt treacherously, though she is your companion and your covenant wife. And did not one do so, who had a remnant of the Spirit? And why one? Because he seeks a godly offspring. Therefore, be careful in your spirit, and let none deal treacherously with the wife of his youth." The man and woman have sinned a Torah sin and a terrible moral failing; it is a sin both between man and his fellow and between man and Hashem. The answer to this, after true remorse and the internalization of the wrongdoing, begins primarily with a strong acceptance on the part of the husband on complete loyalty to his partner. Likewise, the single woman must accept Jewish values strongly, committing not to sin again in the future and not to have relations with anyone except her future husband. Thereafter, they should confess verbally to the sin, and on the coming Yom Kippur they will merit complete atonement. If, as is quite possible, the relations occurred while the woman was tumah nidah (ritually impure due to not immersing in a mikveh after her last menstruation), the matter is much more severe, as relations during nidah is among the gravest sins in the Torah, and there is no difference between a married or single woman in this regard. Thus, part of the repentance certainly includes an acceptance to keep family purity laws in the future. 

Wishing you success. - Menashe Yisrael