How can one deal with relatives who backbite and spread slander, what are the supplications that increase patience in this regard, and should their matter be left to Allah?

Patience is a lofty station bestowed by Allah upon whom He wills. Your effort in maintaining ties of kinship indicates your success and sound thinking, and the Prophet, peace and blessings be upon him, urged maintaining ties of kinship even with those who do not reciprocate. Continue to be kind to your relatives and supplicate to Allah to guide them. Do not expect anything in return for your actions, and minimize interaction with them if it causes problems. Among the supplications that aid in patience are the supplication for distress: "There is no god but Allah, the Most Great, the Forbearing..." and "O Living, O Sustainer, by Your mercy I seek help." Prayer is one of the greatest factors of patience and among the most important means to dispel worry and grief.