My (16f) younger sister (8f) had been talking to an older (19m maybe?) guy she met on Minecraft and it got creepy.

So my 8 year old sister is not a very social kid. She has no friends in school and her only friends are people she’s met on Minecraft. My family and I have been okay with this as long as she doesn’t share personal information about herself, which we are very strict about. She lied about her age to her online friends and told them that she was 13.
She started talking to this guy, who said he was 16, and they became “best friendsâ€. She stopped talking to any other internet friends she had, and told him that she’s 10. Then they skype called each other and we caught her doing it and she got a long talk about talking to strangers and whatnot. The guy DID NOT sound 16. At best, maybe 18 or 19 years old (according to my aunt). Two days later my mother checked her skype to see if they’d been talking and found messages between them saying “I love youâ€, and “We have to keep this a secret!â€. They even referred to each other as boyfriend and girlfriend. She sent him photos of her face and he was like “omg ur so pretty i love u even more now!†She’s 8!!!! You can easily tell that she’s 8!
My parents disconnected her from the wifi and she’s only allowed on internet on a laptop with supervision now. I went on the minecraft server that the guy made for the two of them and called him disgusting and told him to never contact my sister again.
My sister does not understand why this situation was bad. I’ve been trying to get her to truly understand but she just interrupts with “i know!!!†And brushes me off. Also, I feel bad because she’s just unexpectedly been forced to cut contact with her only friend. What can I say to her, how do I make her feel better?
Tl;Dr My eight year old sister was “dating†a guy online that is probably 10 years older than her and we forced her to cut contact. He was her only friend and I’m worried about her and don’t know what to do/say to her.


Source.