How to take defence in advance against criminal allegation

I married in 7th Dec. 2014 on both choice . Wife was studying MA (2nd semister). My parents agreed to complete MA in English.Wife also agreed in presence of her parents to do domestic works as and when required, especially on weekly holidays, Saturday & Sunday . After marriage , going to be completed two years , she does nothing . She always stays on first floor locking the door . She never listen to us. She is called by pushing calling bell to take tiffine ,lunch , diner at grounf floor otherwise she never comes down. If she is asked for a little job, her cruel behaviour, talking manner , obstinate nature spoils the family atmosphere , most of the days she breaks mental peace of us and quarrel goes on for trifling matter. If she is asked for her consent before marriage , she says ," I cannot understand before marriage". It was reported to her parents. Bilateral sitting from both family was held but no change/ no action. Actually her mother supports her daughter indirectly. Parents never respond to our proposal to bring peace in the family and never take feed back about their daughter's daily routine from us. Now she is 3 months pregnant and teaching in a morning school after MA. Now there is no question of domestic job. My mother, 56, still prepares tiffine for her in the morning daily. She has no minimum sense of sympathy. However , My old parents are always afraid in fear of any misdeed by her or legal harassment . My father is a Central Govt. Pensioner . How we can now take defence in advance in absence of her knowledge against any legal allegation from my wife and her parents . Please advise me .