Wiping your computer doesn't really help in this situation. If at any point you went to a website that was a 3rd party website talking about FFXIV, or downloaded any addons for this game from a 3rd party website, Keyloggers can access your password in the blink of an eye. It's a program, .exe file, that reads every single thing you type.

Even if your computer had found something and you were on the game, you were already too late. The best way to prevent this from now on is 2 ways:

1. Get the SE one time password.
2. Type out your password in a word document (or notepad). Stick it on your desktop named something stupid (Mine is named "List of Animes" since I know nobody would care enough to check this out anyway). Inside this type in your password and save. Every time you go to play the game, just copy and paste your password directly into the password box. This way, keyloggers can not pick up what you have just typed. Keyloggers only can register the keys you typed out in the order you typed them. However, CNTRL-V isn't a password

Sorry about your account. Good luck.