Question Summary:
Is it permitted in Shariah to break contact with family members who constantly abuses someone?

Question Detail:

if someone is constantly abused verbally and has shown paitence but can no longer take the stress...and no longer feels able to be around those person[s] does islam allow her to break contact and continue with her own life.....[i.e mother in law trying to turn my husband against me, always advising him against me and our children]

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
We acknowledge your emotional distress and we make dua that Allah relieves you from your pain.
Maintaining the bonds of kinship enjoys extraordinary importance in Islam. Conversely, severing family ties can lead on to a disastrous end.
  
 مَنْ وَصَلَكِ وَصَلْتُهُ، وَمَنْ قَطَعَكِ قَطَعْتُهُ
صحيح البخاري (8/ 6)
Translation: Allah Ta’ala says (to Al-Rahm ‘ties of relationship’) whom so ever shows kindness to you, I shall show kindness to him. Whom so ever break ties with you; I shall break ties with them.
Islam has placed tremendous emphasis on establishing, maintaining and preserving family kinship. Similarly, one is required to be kind to those relatives who are unpleasant or harsh towards oneself.
 
لَيْسَ الوَاصِلُ بِالْمُكَافِئِ، وَلَكِنِ الوَاصِلُ الَّذِي إِذَا قُطِعَتْ رَحِمُهُ وَصَلَهَا
صحيح البخاري (8/ 6)
Translation: The true maintainer of kinship is not one who merely reciprocates. The true maintainer is the one who reconciles ties when they are severed. (Sahih Bukhari)
 
You should maintain ties to the best of your ability according to your health. However, if you can no longer take the stress and it is physically and emotionally harming you and your family then you could keep your conversation with your mother-in-law to the bare minimum[1].
 
And Allah Ta’āla Knows Best
Immad Bin Arshad
Student Darul Iftaa
California, USA
Checked and Approved by,
Mufti Ebrahim Desai.
www.daruliftaa.net