Is it permissible to swear on the Qur'an under duress to abandon speaking to one's maternal uncle forever, under threat of harm?

The forced oath (yamin al-mujbar) is not binding according to the majority of scholars, and nothing is necessitated by it. However, the recognized coercion is compelling coercion, such as threatening with a beating or similar. If it is proven that you were coerced into taking the oath, then it is permissible for you to utter it, and nothing is binding upon you. But if you swore an oath while not coerced, then your oath is binding, and it is not permissible for you to fulfill it, as it is an oath to commit a sin; for maintaining kinship ties with the maternal uncle is obligatory. Therefore, you must break your oath and offer expiation, and you must admonish your brother kindly, explaining to him the gravity of severing kinship ties.