Does my husband become unlawful to me after he committed adultery, based on the Almighty's saying: "The fornicator does not marry except a fornicatress or a polytheist; and as for the fornicatress, none marries her except a fornicator or a polytheist. And that has been made unlawful for the believers"?

If you are certain that your husband is committing adultery, then you have done well in shunning him and going to your family. Advise him and instill in him the fear of Allah's punishment. If he repents, you may return to him. Otherwise, it is not permissible for you to remain with him, based on the Almighty's saying: "Bad women are for bad men, and bad men are for bad women. And good women are for good men, and good men are for good women" (An-Nur: 26), and His saying: "The fornicator does not marry except a fornicatress or a polytheist, and as for the fornicatress, no one marries her except a fornicator or a polytheist, and that has been forbidden to the believers" (An-Nur: 3).