Should one break off an engagement due to strong suspicions about his fiancée's virginity and her committing Zina (fornication/adultery), along with the fear of the consequences of a wrongful breakup or continuing the relationship?

Slandering the honor of believers is among the most dangerous matters, especially accusing chaste women of adultery, which is not proven except by the testimony of four upright witnesses. Whoever accuses a Muslim of indecency without proof is to be flogged and judged as an evildoer. Therefore, you must advise the one who told you ill of the girl to fear Allah and repent. If the girl is upright, then proceed with your marriage, as the loss of virginity does not always mean adultery; it may be lost due to other reasons such as menstruation or a jump. However, if obsessions overcome you and you fear their impact on your life together, then breaking off the engagement might be easier than subsequent problems after marriage.