Legal action against mental torture & black mail with private videos

Hello sir, i am seeking for the righteous action taken against someone who is torturing me mentally. I had a friend and once we got intimate when we were intoxicated. Out of my knowledge he recorded a video of our sexual act. When I tried to cut off contacts with him he tried to blackmail me through those clips. He wanted to get intimate with me once again. He told me that he wants to get intimate once again and after that he will not bother again. Out of my stupidity, I did it but now he is stalking me again and again. He is threatening to kill me and my family and also to expose those videos in public very soon, if I will not get intimate with him at the time he wants have intimation. I would like to get rid off him. I have all the messages where he has threatened me to murder and continuously told me to have intercourse with him.BUT I don't want to involve my parents into this. Thugh my mother knows he is stalking me but she doesn't know the whole story. Kindly suggest me something