I just saw my windows get hacked in my face

So I’m running Windows 10 1809 LTSC and my antivirus is running it just does anything as a normal antivirus but then my discord starts getting notifications like people like a lot of people all of a sudden and I just see full of my avatar like me sending messages full of them, MrBeast scam even though I was watching Netflix and I changed my password thinking someone just had my password. It stopped for like five minutes and then just started re-running. I immediately turned my computer on airplane mode went on my phone and realized the notifications just stopped. I log out of my computer through my phone. I’m reinstalling Windows 10 but not LTC. I don’t know what happened. I don’t know if I changed my passwords. I just installed this operating system three hours ago.