Friends addicted to Internet dating? What do I do?

So I have these two bestfriends. let's just call them A and L. So last year, the three of us got this guy's email from the U.S. (we live in Canada, I'm not gonna say how we got it, its a long story), we didnt know him. We started chatting and chatting with him and got to know him. I was really naive that time so we believed everything he said (he said he was a ladie's man and popular and etc.) He even sent us pictures (which turned out to be his brother, he's a huge liar). We were all infatuated with him and we almost forgot about the real world. Then A's parents found out and stopped A from talking to him, she convinced me and L too. So we all stopped. From that time, all three of us sort of started to hate him for the lies and stuff. Then A started talking to the guy's "sister", which I thought was just him pretending to be his sister. Let's call his "sister" Y. Y started to brag about all her "brother"'s talents and good looks, which lured A into talking to him again. Me and L were hating on him and convincing A to stop. The guy is a huge liar but whenever a girl talks to him, he always sweet talks her and then lures them to his "trap". Now I'm starting to think he's an old pervert doing this everyday on the internet. Just today, I was talking to L about her day and she suddenly brought up the fact that she just talked to him on skype again. I got mad because I hated him ALOT now, when I look back at what I have done, I get very ashamed of myself for talking to that pervert. I asked her if she fell for his tricks again and she told me their convo and how she said they liked eachother again. (as friends, that's what she told me). I have learned a valuable lesson to not be so naive on the internet but my friends have all fell for him again. It's probably gunna bring up more drama. Now A texts him everyday and L said she wants to keep talking to him because he makes her feel confident with herself. I tried to talk them out of it because the internet is a dangerous place and I'm 100% sure that guy is older than 20 and wants little girl's attention. I don't really want to bud in their business but this whole internet thing is going way too far. I've seen A flirt with him on her phone and I think L's gonna do that too. So what should I do? We're 14 btw