<human>: Can you condense the text into a few key points?

I'm not sure if this belongs here or not, but I am terrified of my SO. He is kind for the most part but is extremely malicious and cruel when provoked. He always tells me that he doesn't want to hold me back and would give me freedom if asked, but he's told my friend that if I even so much as think to leave him he'll send my nudes to everyone I know. I don't know what to do about it, I'm scared. I'm still a kid, I'm only 16f (he's 20). He has helped me through hard times and he is a fun guy to webcam with and be with when he is in town, but he genuinely frightens me to the point where I am scared to let myself get close to someone else who lives in my area. My feelings for my SO have diminished as he began to excessively flirt with my best friend. But I continue to remain in an LDR because of fear and I've only just admitted this to myself now. I would do anything to be rid of him without my social life at stake. We've been friends for a year and in a relationship for 5 months.
<bot>: My SO is threatening to send my nudes to everyone I know if I leave him and I am powerless to stop it.