Does not forgetting a sin and constant fear mean that God has not forgiven? And how can one know of forgiveness, and does repentance make its doer among the righteous? And must one divorce her husband or marry him off as expiation for the sin?

The door of repentance is open. If you repent with remorse and a firm resolve not to return [to sin], Allah will forgive you. Allah, the Almighty, said: "Do they not know that Allah is He who accepts repentance from His servants and receives charities and that Allah is He who is the Accepter of repentance, the Merciful?" And 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.'" The one who repents from a sin is like one who has no sin, and the repentant person is not punished for his sin, as Ibn Taymiyyah said. A condition for sincere repentance is to avoid the causes of disobedience and to cut off the paths leading to it.