How does a married man who has been tempted by another woman rid himself of his sin, especially since he has started praying and intends to perform Hajj this year?

The sin of Zina (fornication/adultery) is among the grave sins and abominations that must be avoided. Allah has warned against it, saying: "And do not approach unlawful sexual intercourse. Indeed, it is ever an immorality and is evil as a way." (Quran 17:32). Its prohibition is even more severe for a married person. Therefore, one must hasten to sincere repentance, for the one who repents is like one who has no sin. Allah loves those who repent and forgives all sins, as He said: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" (Quran 39:53).