How can one reconcile maintaining ties of kinship with a foul-mouthed brother while preventing one's husband from communicating with him out of fear of sin?

A husband has the right to prevent his wife from leaving the house without his permission or from bringing someone he dislikes into their home. However, he does not have the right to prevent her from contacting her kin (relatives), and she is not obligated to obey him in this regard, unless it leads to harm, such as corrupting her morals. Therefore, your husband does not have the right to prevent you from contacting your brother for the sake of maintaining kinship ties. You should strive to reconcile with him by communicating, being patient, and overlooking his shortcomings. You will be rewarded by Allah for this, as mentioned in the hadiths regarding the virtues of maintaining kinship ties and enduring harm with patience.