What should my friend do?

So, my friend and I are both in chorus and everyone in chorus is pretty close in a way. So we all talk. My friend talks with this boy in chorus in a different class on the app kik. He's been trying to get with her for a while now but she has a boyfriend (which if you ask me, I would have stopped talking to him a while ago). He kept asking her to send nudes but she wouldn't until one day she was trying to send him a picture (of idk what) and she accidentally sent him a nude picture of her to his phone. After days of constant begging, he said he deleted it and sent a screenshot of his picture gallery but I don't think he deleted it. Now he keeps threatening to tell her boyfriend if she doesn't send him another nude. She lied and told him that she told her boyfriend and that he forgave her. I told her to tell someone like the counselor at our school so he'll stop bothering her and he so he won't walk at graduation but in North Carolina, it's illegal to send and ask for nudes if you're under 18. So not only will he get in trouble, she will get in trouble too, it's under child pornography laws. I don't know what to tell her. So that's why I'm asking the women of eve because most of you have really good advice and are very blunt.