Just looking at the information provided above it would seem likely that "Vine"'s Discord account got hacked - as well as his email which might have used the same password.
Since you only exchanged those two methods of communication, your best course of action would be (as @ShangXian already suggested) to contact the school you both visited. They probably have strict guidelines to not disclose private information, but you could give them your email to forward to "Vine" or their parents.
Feel free to send me a PM if the school refuses to forward your contact information. (Even if they tell you they won't do it doesn't mean that they cannot be persuaded with an improved approach.)
ShangXian
Hi, I read this blog while surfing in artists news section and I noticed your post. I am just a stranger who happened to read this story so I don't know how much my small contribution may actually help you feel a bit better, but a thing I may suggest you is trying to contact the private online school your friend went and see if they can answer your questions. You can say you went to private online school and met him there.
Maybe they can help you or maybe not but asking doesn't cost anything. I am really sorry to read you are worried, again I am just a stranger but still I know the feeling of not being able to be in touch with a friend. It happened to me with a funny and fantastic person with whom I talked often but then they deleted their account and I couldn't reach them anymore. A friend of mine told me what happened and I am still very sorry this person went into a toxic relationship. But back to your worry, I do really hope your friend is doing fine. When you and him talked, did he talk about his family? Did you ever know the family? Of course don't reply to me here, I know it's personal but maybe you can try to reach the family and ask. It could be ghosting, I don't know.
Hoping things will solve for the better for both of you, I wish you all the best.
HollyberryAndSplice
Thank you so much for the comment, it helped more than you know.
Also I'm sorry to hear about what happened to your friend as well, that sounds worrying and I hope everything turned out well.
And all I know is that his mother is a very strict woman. For all I know he could've gotten in trouble and had all of his internet / contacts cut off by her, though I'm still not 100% sure.
And again seriously thank you so very much for commenting this.