Has the questioner erred by proposing to a girl with whom he committed illicit acts? And should he now leave her and search for another righteous girl, or should he continue with her in the hope of repentance after marriage?

You erred by being lenient with this foreign girl, and Satan exploited that. You both must hasten to repent. The fiancée remains a stranger to her suitor until the marriage contract is concluded. It is not necessary for you to be punished in kind in the future, so do not preoccupy yourself with thinking about that. Sins extinguish the light of faith, but whoever repents, their heart returns to its original state. We advise you to marry her if she repents. If you do not wish to marry her, there is no harm in breaking off the engagement.