salaam, i had a family dispute and my eldest brother spoke very rudely to my mother and swore so i basically cut all ties with him and almost ended up in a fight with him

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 is His slave and Messenger.

The parents – especially the mother – have a great right on their children and Allaah ordained us to be kind and dutiful to them even if they are non-Muslims and forbade severing ties with them and considered this as one of the great major sins; for more benefit, please refer to Fataawa 87856 and 89078.

Therefore, if what you mentioned about your brother is true that he spoke very rudely to your mother and swore at her, then he has indeed committed a grave sin as he was undutiful to his mother and he has severed the ties of kinship with her, so it is feared that Allaah may inflict him with an urgent punishment if he does not repent to Him. Therefore, you should advise him to sincerely repent and you may refer to the conditions of repentance in Fatwa 87903. Also, for more benefit, please refer to Fatwa 88129.

As regards you cutting relations with your brother, then if you did so as a way of deserting him and condemning what he had done and hoping that deserting him will be beneficial to him, then this is permissible. However, if it is predominantly thought that he will not be deterred by deserting him and that it might make him even more stubborn, then in this case it is better to soften his heart instead of deserting him, and to advise him in a nice and gentle manner and remind him of Allaah and of the evil subsequences of what he did as he might repent and ask his mother to forgive him. For more benefit on the conditions of deserting someone, please refer to Fataawa 84976 and 86090.

Allaah Knows best.