Need to know the steps for divorce

I am a PhD student. I have been married since 5 years. I have a daughter of 1.5 years old. From the beginning of my marriage I am having problem with my husband and in-laws. Many times I was physically and mentally tortured by my husband. Now, it is like that I am no more interested to continue this relationship, though my husband is repeatedly pretending to be sorry for whatever have happened. But the fact is I have lost all the emotional attachment with them. From last 8 months he was in abroad and I was taking care of my daughter alone. My father is also staying with me since feb 2015. Couple of days before my husband has returned all of a sudden after loosing his job. He is repeatedly saying sorry and to accept him otherwise he will commit suicide. It has happened many times that he physically tortured me and later came saying sorry and again did the same thing. However, I strongly think that, staying with him is only ruining rest of my life. So, I want to go for divorce. I would like to mention that I want to keep my daughter's custody after divorce. Kindly, advice me how can I proceed. Thank you