What are the possibilities to get divorce and custody of my kids?

I am a 38 years old married and employed woman. I was married 10 years ago and got my job after marriage. I got posted to my native and am living in my maternal house since past 4 years with my children aged 8 and 10 years as my husband is posted in another state and he has been trying to join us here by taking a transfer. We had a cold marriage in which adjustment from my side was the norm. One year back my husband discovered about my relationship with a colleague after going through my mails etc. from then onwards he visits my maternal home stays for weeks and there were regular incidents of physical violence, abuse and threat of killing me, kids and himself but these were done at night, behind closed doors, when all my family members were asleep. I had not told my family about these incidents and tried to hide my injuries on the hope that things may improve and also due to the fear I had about him. We have not had conjugal relationship for the past one year. Recently he took away my kids and put them in my in-laws home and admitted them in a school. I decided not to tolerate this and have asked for a divorce but he threatened me that he would expose my mails to my family and also by trying to come to some understanding with him but I have made the decision to leave him as we don’t respect and love each other and rather than get abused before my children I prefer to come out of this relationship. I have told my parents about my decision and they are discouraging me from going for a divorce citing the societal pressure in taking such a step. The present status is that he doesn’t want to send the children to me and says only way is for me to go and stay with him. I am unable to understand what to do? As there is no respect and trust between me and my husband, I don’t want to live with him. Please suggest me what should I do? How can I divorce him and what are the chances of getting the custody of my kids?