ما عقاب الزانية مع غير المسلم وكيف تكون توبتها وهل تُقبل؟

Allah has forbidden fornication and adultery, associating it with shirk (polytheism), and has threatened its perpetrator with severe, multiplied torment. However, He—Glory be to Him—has opened the door of repentance for whoever repents sincerely, promising to accept it and to erase evil deeds and replace them with good deeds, as He says: (Except those who repent and believe and do righteous deeds; for them Allah will change their evil deeds into good ones. And Allah is ever Forgiving, Merciful) and His saying: (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").

Therefore, this woman must repent with a sincere repentance, and increase her istighfar (seeking forgiveness) and acts of obedience, and change her companionship and environment to righteous ones, knowing that fornication/adultery is forbidden with both disbelievers and Muslims alike.