Threatening calls and sms

I have been married for 12 years now.Several times I have wanted to get out of this marriage but could not succeed because of fear of my husband, society and most importantly my own weekness of not responding on time. He had torn all my professional documents once and threatened to tear once again. I gave police complaint for domestic violence and stealing of documents but withdrew later. He never attended counseling session organized by women's cell of police. My husband is a criminal who has time and again cheated women for money by promising job or marriage. I have 2 children. When one of the women came looking for him, he escaped from the house rented by me. Since then I have not let him back in.(2 months)I have just come across his marriage certificate with another woman held 1 and half years back. Now my husband who has hardly worked for a total of 12 months in the past 12 years wants to join back with me. He keeps sending threatening and abusive calls and messages and also emails to my office mail.I have started recording all. There are 2 cases going on in bangalore and kerala against him for similar fraud offence.he was also jailed twice. Can the law help me to get rid of this man without losing my 2sons(11 and 8 years) to him. They too dislike him.i held on to him fearing social stigma. But he has brought lot of disrepute to family already.