how to deal with online blackmail?

[proudball651]

okay, this will be long, but i really need your help. i'm desperate

i have this problem since around 1st or 2nd grade of senior high (i was 16 at the moment, this year i'm turning 19) about a guy who live in Europe.
Back then i use this online live webcam chat for fun, i recklessly use it and just be friendly people i met there, even if it's kinda sexual, i just comply because at the moment, i have no idea about the consequences.

so one day i met this "girl" that ask me to "play" with her. the idea seems interesting for me, and i honestly did everything out of curiosity. i comply then i did some stuff (take off my pants and shirt and start to touch myself) when suddenly her video changed to a guy.
then this guy start to threat me. he said if i don't keep "playing" with him he will spread around my video.

I was so scared, i just say yes. after that incident, he ask for several "tickets" for having a "play" with me. this "play" include me touching myself for his satisfaction. after that one time, i do my best to omit my face from every video chat we did.
I trust him in hope he will delete the video (he promised that). and then he said, okay, we're done. then i block his msn. but not long after, he contact me through my facebook (i'm guessing he searched for my name), then threat me the same thing. saying "turns out that the video is still there, my brother saw it and i need to bribe him. don't you think i could get more ticket?"

the same thing happens again. we use skype this time. after we done with this one, and i block him, he contacted me on twitter. i was really at lost and so scared. i tried to ignore but he kept contacting me through many social networking media until i agree to do one "last"

but then just now, he sent me a message through skype with a new account. to accept his acc and do another one, or he will spread the link of my video.

here's the situation:
1. i was 16-18 during all of this. next september i'm 19.
2. no one knows about this, since here, sexual matters are somehow considered taboo and unproper.

what should i do? i tried ignoring, try to talk to him, threaten to call the police (but i never did since i don't know how and he's overseas. i'm in asia), and block every account, delete those, but none works. he still appear just now. (i have changed my skype to get lost of him)
and do you think he really have my video? or he's just bluffing?
what should i do?

please help
thank you.