I NEED HELP

I've been talking to this guy online for a couple weeks and he kept asking for nudes. I was so so so stupid and I decided to send them. It was on Snapchat so you can see if the other person has screenshotted them or not and they all said that he hadn't. But I found out he had been saving all of them and now he's threatening to post them. The catch is that he only has my Snapchat and none of my info, apart from my age and what country I'm from, so if he did post them on Snapchat, Instagram, Twitter, or any other social media, I don't think anyone I know would see them. He says if I don't do certain things for him, he's going to post them and "ruin my life." I want to tell my parents because I'm genuinely scared of this guy, but I'm afraid they'll be disappointed in me. (I forgot to mention he not only has pictures with my face in them and videos.) I realize this was a really stupid choice on my part but I was wondering if anyones ever gone through the same thing or has any advice on what to do stop him. I've tried talking to him about it multiple times but he just brushes me off and says "send more" and it makes me so uncomfortable. I'm sorry this is all over the place but my mind is racing and I'm freaking out.