Divorce related query

Hello Sir, My sister was married to our relative boy 7 months ago. He was alright in the beginning after a month he started forcing her to go for work and also started stating silly complaints to her sister(I.e. me)And they live in bangalore and her in-laws are put up at Mysore. Whenever she visited their place the mother in law would taunt her everytime and make big issue out of every small thing. And after an heated argument at their place in March, my parents went and my sister came along for a week. After that they have started saying we don't want her. We contacted the boy and he also states that he doesn't want to live with my sister. After much plea to his parents they remain of the same opinion and finally we contacted the boy on phone 15days ago and he said he will come for sitting and talking to girl one on one but which he never did and has sent a divorce notice. What should we do now and the boy has only one kidney which he had not mentioned to us before marriage but has told the girl after marriage. What can be done