Is the marriage that took place between the questioner and the aforementioned person Islamically invalid, based on his statement that it was for the purpose of "making sexual intercourse lawful" and that he does not want children, or is that merely a statement made in a moment of anger?

For a marriage to be valid, the presence of a guardian (wali) and witnesses is required. If these conditions are met, the marriage is valid, and its non-registration in court does not affect its validity. The husband's statement that he married only for pleasure does not invalidate the marriage. The subsequent pregnancy attributed to the husband cannot be denied by him except through li'an (oath of condemnation), and procreation is a right of both spouses. The husband must treat his wife kindly and justly, and maintain equity between her and his other wife regarding lodging, financial support, and clothing. It is advised to be patient, offer sincere advice, supplicate to Allah, and seek assistance from influential individuals. If the situation persists, the woman has the right to seek divorce due to harm.