All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If the woman whom you mentioned in the question is really mistreating her husband and harms his relatives and neighbors, then she is disobedient to her Lord and oppressing His creatures. Her arrogant behavior towards her husband is considered recalcitrance from her side and the Sharee’ah has clarified how to treat a recalcitrant wife; for details, please refer to Fatwa 85402.
Therefore, you should advise her husband to be strict with her and use his right of guardianship over her and discipline her according to the method that is mentioned in the Sharee’ah. Also, you should appoint some rational people from the family of the husband and the family of the wife to study the matter and look for a solution if their intervention is needed.
If she becomes righteous and reconciliation is achieved and the problem is solved, then praise be to Allaah, otherwise the husband should be advised to divorce her as it is more appropriate to divorce such a wife.
Indeed, it is confirmed in the Hadeeth that was reported by Al-Haakim in Al-Mustadrak that Abu Moosa Al-Ash’ari narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: ''There are three kinds of people who would supplicate Allaah and He will not respond to their supplication: a man who has an ill-conduct wife and he did not divorce her….” [Al-Albaani graded this Hadeeth as Saheeh (sound)]
Also, the relatives of the husband may desert her if they believe that deserting her would be beneficial for her.
On the other hand, if what you mean by his brothers and sisters cutting off relationships with him by not visiting him in his house as a way of avoiding the harm of his wife, then this is permissible; it is possible to keep ties of kinship by other means, like a telephone call and the like. However, if what is meant is that they have totally cut off relationships with him, in a way that they neither speak to him nor say Salaam to him, and the like, then this is considered as severing ties of kinship and it is a grave and major sin.
In any case, we advise all of the brothers and sisters to reconcile and not fall into the trap of the devil who is keen to use all means to separate those who love each other. For more benefit, please refer to Fataawa 83031 and 84976.
Allaah Knows best.