I have had a broken engagement before. Do I need to tell the man who is proposing to me now?

You are not obliged to tell him the details, but being open about the fact is usually better than him hearing it from someone else. A broken engagement is not a disgrace and not a sin; sometimes it is the wisest decision. You do not need to recount the faults of your former fiancé or his family. Use a short answer, for example: ‘I was engaged before, but we were not compatible and parted on good terms.’ If he asks further, answer honestly without speaking ill of anyone. The Prophet ﷺ said: “Whoever believes in Allah and the Last Day, let him speak good or remain silent” (Sahih al-Bukhari 6018). His attitude to this disclosure also gives a picture of his maturity. See the ruling on breaking off an engagement.