What can I do to avoid Allah's punishment, and is it true that there must be torment and purification in the grave or the Hereafter, after I repented from committing Zina twice?

Adultery is a grave crime for which Allah has promised a multiplied punishment on the Day of Resurrection, except for those who sincerely repent with a truthful and unreserved repentance, for then Allah will transform their evil deeds into good ones. Whoever has fallen into this abomination should continue to repent and feel remorse, distance themselves from the causes of the forbidden and temptation, and increase in good deeds such as prayer, remembrance of Allah, recitation of the Quran, and charity, especially secret charity, as Allah Almighty says: "And indeed, I am Forgiving to those who repent, believe, and do righteousness, and then are guided."