What is the ruling on marrying a woman who committed adultery before and after marriage, and is now repentant, knowing Allah’s saying: "The fornicatress – none marries her except a fornicator or a polytheist"?

Since you repented before marriage, your marriage is valid. What happened after the marriage, namely falling into haram, does not affect its validity, because the adultery of one spouse does not invalidate the marriage according to the general consensus of scholars. As for the verse, "The fornicator does not marry except a fornicatress or a polytheist...", its meaning is a prohibition for a chaste Muslim man to marry a fornicatress, and a prohibition for a chaste Muslim woman to marry a fornicator. Therefore, what you fell into of haram does not affect your marriage, and you must remain firm in sincere repentance, strive in good deeds, and conceal yourself.