Harassment and legal action

I have been into a relationship with a Hindu guy for more than 10 years. I have adjusted with this guy to the extreme level. He became alcoholic and very casual towards life. After so many hardships, issues and his false promises, I broke and moved away two years back. I got married to a nice guy after the advice of my parents and started a new life very happily. From these two years, he sends text messages, makes many pesky calls every day even the number has been blocked. He sends a threatening message like "Jaan se Marwa Sakta hu." He even claimed to have the false marriage certificate from Arya Samaj, Lucknow about which I came to know recently. He even sends messages to my younger sister, my mother, and my close friend. In action, we just registered a police complain, calling women cell number 1096 in New Delhi. He lives in Lucknow. What are the legal actions which can be taken against him? He has been such torturing headache to my family and even to my husband. I live in New Delhi and he lives in Lucknow. To what maximum extent can he be prosecuted in the court of Law? Can we approach National Human Rights Commission too in this regard? Please help as I am highly depressed.