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 it is true that your brother refuses to divide the inheritance of your father and give everyone his right, then he is absolutely wrong and unjust.
Therefore, we first advise you to be patient with him and supplicate Allaah to guide him. You should continue to advice him in a soft and nice manner and seek the help of those who may influence him.
Then, if he still refuses to divide the inheritance amongst you, you may threaten him to take the matter to the authorities, and it is permissible for you to sue him if you wish to do so.
As regards deserting him, then this is something permissible in such cases, but if you predominantly think that this will not achieve any benefit, or cause greater harm, then it is better not to desert him.
For more benefit, please refer to Fataawa 86772 and 84390.
As regards your mother, if she is poor, or has money but she is prevented from it, then it is her well-off children –whether males or females –who are obliged to spend on her.
Allaah Knows best.