blackmailing from my exboyfriend

With my fault unexpectedly i met a guy who is brother of my friend. I messaged him in facebook at that time i think that fb accout is my frnd account.. After sometime i realize that he is my frnd's brother So msged him frndly for some days .After few he proposed me but i didn't accept his propsal .he called me lot of my time and also msged me. So i put his number in block list.he called me from different numbers and he always requests me to accept his love .finally he makes to accept his love . At that time actually I'm not interested on him .and i didn't about him . After few days i understand about his character.he is a selfish person he always ordered me what to do ? he didn't understand about my situations i tired all of these . Sometimes we become close . After knowing he's character we break up . But he still blackmailing me to love him and to marry him. He want to come to my home and he will reveal about my relationship with him to my parents. If my parents know about all these issues they can't tolerate this . They may get anger on me and all family fame will get down .i don't know want to do in this situation. I don't want to keep this terrible situation on my parents. I want to this problem myself.