If a man torture his wife physically, mentally or emotionally and she have to face injustice from husband then what should she do in this situation. can she initiate divorce herself? what Islam says about this?
To answer your question : YES , she absolutely can .
It is called Khulaa (Arabic for being ripped off from something , in this case the marriage ) , an overview of the proceedings are described here.
Khulaa is strongly supported by Sunni Islamic institutions worldwide , I also believe Shi'as have a similar system (needs confirmation though) .