Is the questioner accountable for the sin of severing ties of kinship with his brother because of his brother's wife, and what is the way to guide the brother if he is certain that he has been afflicted by magic because of his wife?

Islamic law forbids estrangement and abandonment between Muslims, especially among blood relatives, as cutting off kinship ties is a major sin. The Prophet, peace and blessings be upon him, commanded maintaining ties of kinship even with those who sever them. The wife has done well by encouraging the maintenance of kinship ties. You must strive to reconcile with your brother with kindness and advise him of the obligation to maintain kinship ties and the prohibition of severing them. After that, there is no sin in shunning his wife if she shuns you. Furthermore, accusing the brother's wife of witchcraft is not permissible without clear evidence.