Against Someone Who blackmailing that they commit suicide ..

Hii sir/ madam .. I am a girl. I have a social media page regarding studies .. Nearly 1 and half years before , a guy became my friend in that page. He was 7 months younger than me. So i texted . Then we became somewhat close .. like friends. On that time. ., i was alone .. I have no contact with most of my friends. . I had small circle because of my aspirant journey and mental stress .. I said this to him ..And said he was the only one talk to me at that time daily. So i was attached to him. . But he wrote poem and short stories for me. . its like a love feel. But i said. .this will not happen. I can't marry you. I have a crush on someone who proposed me .. he also accepted everything . after 4 months , i went to my friend marriage and put status as. Happy day after long time. .he asked that then u r not happy with me these days ? Its like a psycho .. he asked me that i didnt post a single status for him. So he is not important to me . I was stressed.. And i was avoiding him. And after few months .. said gud bye. And no contact for a year. . And i did a mistake that. I texted him how r u .. He then Visiting my social media page and saw my posts. . story highlights .. and my comments in other social media page comments. . everything he analysed. . and texted me in a wrong way. . because i was casually commented in others page. . posted story for my mom birthday , sis birthday. Etc .. he asked me that u said. . u r not talking to anyone and wont put status for anyone. And even u didnt said ur name on our first chat ..but now u r like a easily available girl. .etc .. i was hurted. . called him and texted many things .. he said. I cheated him and he want to commit Suicide he can't tolerate that i am talking to everyone casually. . So he asked my username and password. . i didnt give him. Then he said to deactivate that account .. i was deactivated just because of courtesy .but he said that in that account i texted everyone in a wrong way. So i deactivated and not giving username and password. .i tried hard to explain everything .. and said we are not in a relationship .. so thats my wish. I can do anything .. u have no rights to interfere. . but he didnt accept. One time i said he was younger than me. So i called him bro ..he slightly cut his hand with knife and sent me a picture. . i cant tolerate. . i said. I am going to marry someone. Engagement in this month. .but he said that was not his problem .. he only cant tolerate that i was friendly in that page. Atlast my friend talked with him as my fiance . Problem not solved even now .. i cant handle. He called & texted me in unknown number and social media account .i blocked and avoiding until now. Today he sent me a quote like he will die . I cant handle these things. Please help me .. thank u in advance.