Are these merely whispers that I am experiencing, or could my marriage be invalid, based on the noble verse which states that "the fornicatress – none shall marry her except a fornicator or a polytheist," and I doubt the validity of my marriage to my husband, who is neither a fornicator nor a polytheist, knowing that I am keen on being faithful to my husband and living a lawful life?

These obsessive thoughts are pernicious ailments with severe and dire consequences, and they must be dismissed. The aforementioned marriage is valid as long as it fulfills its conditions and pillars. As for what is called "blood marriage" (mixing blood), it is not a legitimate marriage; rather, it is from the inspiration of Satan and is forbidden. Regarding the verse in Surah An-Nur, the most preponderant opinion is that it indicates the prohibition of marrying an adulteress before her repentance, and this does not apply to the questioner because she has repented. Informing the fiancé of the details of the immoral act is not permissible شرعًا (legally/religiously), and it is obligatory to conceal one's sins when falling into disobedience. The questioner's marriage is valid because at the time of marriage, the description of an adulteress did not apply to her, and marrying a woman who has repented from adultery is permissible by the consensus of the people of knowledge.