So, I met this dude on Twitter, who had 4k followers, and offered to shout my channel out if I make a lets play of his "java game". So I added him on Skype, and he sent me a Java file. Like an idiot, I accepted it, although I had my doubts. AVG said it's a trojan virus (can't remember the exact one), but the dude just said AVG sometimes makes mistakes. So, I clicked on it and nothing happened. After that, it said there's a trojan in server.exe, which is a file in my Minecraft game. So I just deleted the file he sent me, and moved on with my life. After a few days a java chat box appears. It said something along the lines "You thought I was gone? " and then he said "My virus is uninstallable." The file he sent me appeared on my desktop again. As I realized that I put inportant info like my paypal (address, phone number) in I instantly disconnected from the internet and deleted java.
Of course, I do know that his virus is not uninstallable, and that he said that to scare me. However, I have no experience with viruses, and I need someone who is able to identify this kind of virus and know ways to prevent it. If I reinstalled java would he be able to do that again? What kind of control did he have over my computer, since the Java chat box appeared by itself?
As a 13 year old who isn't a native english speaker, I apologize for any grammatical errors. I'm really concerned about the info I gave. Please help me so I do not get in trouble.
Thank you.
Added (1). I also forgot to mention that I have win7. The hacker can't acces my computer when it's disconnected from the internet, right? Right? I'm really scared.