How do I deal with my ex-fiancé's false accusations that led to the dissolution of my engagement to my cousin's son? Should I confront my cousin's son and the family to clear my name, or should I be patient and seek recompense from God?

What the young man did was an injustice, and Allah will not let the right of the oppressed be lost. The supplication of the oppressed is answered, and Allah helps the oppressed, even if after a while. He grants respite to the oppressor, then seizes him. There is no blame upon you for defending your honor and repelling evil speech about yourself, whether before your family or your cousin. This is your duty, for the Prophet, peace and blessings be upon him, defended himself against accusation by clarifying that the woman with him was his wife. You must seek Allah's help and strive for clarity in your actions and words to avoid suspicion. It is permissible to mention one's good qualities when there is a religious need to do so, such as defending oneself or having one's statement accepted, not out of boastfulness, as the prophets, peace be upon them, did.