My ex bf trying to ruin my life what to do

I m very tensed because of my ex bf we were in a relationship and he started pressuring me for sex a lot, and to support that he made promises that he will marry me nd all. I succumed to all this and finally gave in after a year but to my surprise he was doing all this just for sex and left me three days after that I was scared for my dignity in college so I begged him to be back, he did come back but for next one year was torture for me he used to abuse me all the time verbally, say bad words to me and my family. now he has broken up with me forcefully for another girl and if i go to talk to him he abuses me again and threatens me to ruining my life if i tell anybody. How can I punish him???Is there a law for this case??