Is it permissible to marry a girl with whom I had a physical relationship before converting to Islam, knowing that her parents refuse the marriage, and there is a law in her home country that obliges whoever deprives a girl of her virginity to marry her?

You must repent to Allah for this grave sin, and increase your seeking of forgiveness and performing righteous deeds. It is not permissible to marry the girl with whom you committed adultery unless both parties repent, her womb is proven to be clear, and her legal guardian agrees. Otherwise, seek out a chaste girl.