How to get separation being a govnt servant ,my brother is helpless.

I(eldest daughter) along with my widow mother and brother stay in house we are Hindus , .My brother got married in 2017 it was aarrange marriage , from the very beginning his wife showed disliking towards us . from very 1st day she did not wanted any family members interference and so we dicided to keep both of them separate in different house but in same campus . Inspite of keeping both of then separate still she did not liked my brother talking with his sisters and mother, she did not wanted her husband to keep relations with us , my brother also had to take care of his mother , but his wife dominated him in each and every decision. One day she called her father and and went back to her hometown without any reason and said she will not come , it is 15 months since she left , and now she wants my brother to file divorce and giving threat of 498 . What to do now ? What r the consequence if my brother files divorce, as he also wants to end the relation , he is a govt servant .