@ Author
A rather unfortunate lady's case before us. It is a freak accident of mother nature is what it is called in medical fraternity.
Nevertheless; because of our culture it is not easy for our women folks to socially talk or complain about s*x. A doctor has to uncover this problem by always asking her at the appropriate time (age). Past omissions are bygone is all that could be said now for her. In my experience 2 patients of mullerian agenesis had such s*xual problems hidden during their marriage from their husbands and one of them was divorced because of this exact problem in 1992 by HC in MP on appeal. There is another more or less parallel case bearing similar medical facts which was ordered by Supreme Court of Philippines in 2008 where 'name and gender' was changed on request of the female later on.
Now onto your questions;
1. Please guide me how should i proceed to get him divorce.
Take: The brief smells of "suppression of material facts" and using S. 12 (1) (c) of Hindu Marriage Act nullity of marriage can be prayed for. Use the existing medical records and bring in on to the box the case dr. as material witness for cross examinations.
2. What are the chances for divorce.
Take: Very very high. What your side has to prove via medical records and witness deposition is that her condition is one which existed at the time of the marriage which was concealed and amounts to suppression of material facts and was only discovered over persistent medical examination of the lady "and continued to be so until (his institution of the proceedings)".
3. In this case like normal divorce case, my brother have to pay her something to get divorce(as my sister-in-law is suffering from this disease by bearth so her family was aware of it ),my brother is unemployed.
Take: No, this case pleadings are not like normal divorce case pleadings, the remedy in favor of your BIL will rest highly relying on existing medical records that his side got and constituted medical board cross examinations based, nevertheless, your BIL has not to pay anything as his status at the time of filing divorce based on "suppression of material facts" is that of 'a student' and a student is presumed to be 'un-employed' and living on genetic borrowings for studies from his parents/relatives or on scholarships (if any) as the case may be.
Be prepared for counter cases from her side though!
