Harassment by colleague, what action can i take?

When i was a college student i 've no knowledge on love and other activities.i was very friendly to everyone,but others had no courtesy and had me for money.i was like a girl to trust someone and after cried for their attitude. But am heartily very pure and yes am pure on all way. i was in relationship with my classmate.I loved him and taken more pictures.i never thought to cheat him.But he started torchering me to meet up in front of my hostel if i miss to see him. I left my job as he has shouted on floor of training institute where i had worked as a trainer. i thought he wont suit for me.then i started leaving him. Because of that we started fighting each other. i was started securing my life from him.But his blackmailing email on my workplace made me go mad and started killing me every second. i lost my peace and happiness then i started living my life only for present moment as i tho