Should I stay with my fiancé who feels guilty towards a female colleague with whom he made a mistake before our engagement, and who now claims she lost her virginity because of him, knowing that he wants me as his wife and refuses to discuss this matter with anyone for fear of scandal?

The extent of the relationship is unclear to us. If it reached the point of fornication, then he must offer sincere repentance, for Allah Almighty says: "The fornicator does not marry except a [female] fornicator or a polytheist, and none marries her except a [male] fornicator or a polytheist, and that has been made unlawful for the believers." He must sever his relationship with the woman, conceal his sin, and not inform anyone. As for you, you are a stranger to him until the marriage contract is concluded, so it is not permissible to be in seclusion with him or to be overly familiar with him. Any meeting should be in the presence of a mahram (definition) and only when necessary. You must inform him of the Shariah ruling. If he repents, then complete the marriage. If he insists [on his sin], then there is no harm in breaking off the engagement. We advise performing Istikhara (prayer for guidance) in every matter.