Is it permissible for a woman who is engaged to break off her engagement to a man who has admitted to his bad past and to communicating with his ex-girlfriend, especially since she is hesitant due to her social circumstances and fear of repeating the experience of her first broken engagement?

Firstly: The suitor should not reveal his bad past to his fiancée, for he is obliged to conceal it and repent to Allah, as Allah the Almighty says: (Indeed, those who like that immorality should spread among those who have believed will have a painful punishment in this world and the Hereafter), and as the Prophet, peace and blessings be upon him, said: (Avoid this filth, and whoever commits it, let him conceal himself with the concealment of Allah and repent to Allah), and (All of my Ummah are pardoned except for those who publicize their sins).

Secondly: The suitor's sincerity in wanting to repent is evident from his confession and oaths. Given what the questioner endured in her first experience, it is advisable to expedite the marriage to cut off the other woman, with the necessity for the suitor to completely sever his relationship with that woman. Otherwise, suspicion regarding his repentance would be justified, and marrying him would entail risk.