A detailed question was sent where a brother in law was committing wrong deeds with his sister in law. The questioner wants to know if it’s ok to severe ties with him.
You should make sure that he is not living in the same house as your sister-in-law. In one hadith, Rasul e paak salallahu alayhi wasallam said, “A man and a woman are not alone except Shaytan is the third.”
Once, a saint saw a dream in which he asked Rasulullah salallahu alayhi wa sallallahu regarding the above Hadith. He added “Would shay tan be there even if both parties pious people?” Rasulullah sallallahu alayhi wasallam replied “Even if the man was Junaid Baghdadi and the woman was Rabia al Adawiyya, shaytan would still be present.
So you have to make sure that this man is not left alone with your sister-in-law or any other woman for that reason.
Secondly, your situation is quite sensitive so we won’t say that you should stop talking to him altogether. Har ek ke saath dil laghi nahi karna hai, so you don’t have to be happy and jolly with every single person. Just be yourself and don’t worry too much! Speak when spoken to and ask him how he is but don’t get too involved.
Allah khayr ka mu’amala farmaye rahm farmaye zawjayn ke darmiyan apas me muhabat aur ulfat inayat farmaye. Ameen