Mental harassment

My brother's wife abusives our mother in front of us. at the time of marriage we did not demanded anything, not even a penny but they told us that they will give 4 lakhs to us for my brother's education loan. after marriage they refused to give it to us and we did not debated on this topic thereafter. my father has passed away long time before my brother's marriage and my mother has a shy nature. they took advantage of this situation and started to interfere in my brother's life. my brother's wife is too dominating. she goes to work in the morning at 10 and comes back at 10 in the night. she is a physiotherapist. so takes extra patient for extra earning which is not liked by my mom. on asking her to leave the extra visits she made to patient's house she gets furious. she abuses my mother. she likes to wear small clothes. my mom asked her not to do so. she again abuses my mother. she also had abused my brother in front of us many times. and after abusing she apologize to everyone but she keeps on repeating this. she does not talks to my brother nicely. she talks to him like he is her servant. on discussing this situation to her parents, they ask us not to interfere as it is their matter. my mother and i lives in delhi n my brother with his wife lives in mumbai. we want to get rid of her...please help us by giving a solution..