What is the ruling on a man marrying a woman upon whom he عقد قران (solemnized the marriage contract) in the presence of her mother and two witnesses, knowing that he had sexual intercourse with her before the marriage contract, and does she become permissible for him after divorcing her three times?

You must repent from adultery. The woman's self-marriage is invalid according to the majority of scholars, and this is the most preponderant opinion. Your triple divorce of the woman is valid, and she is not lawful for you until she marries another husband willingly, he consummates the marriage with her, then he separates from her, and her waiting period (iddah (definition)) ends. It is not permissible for someone who believes a marriage contract to be valid to base a ruling on its invalidity that aligns with his desires.