I forgot I was logged into my VPN and tried to load diablo and now I get the "you have been disconnected from battle.net" screen.

is this permanent?

If it's your first time, probably not

most likely a 2 week ban

Seen this happen to friends for VPN and it was a two week ban each time

I've read each login attempt resets time counter. Do you know if this is true?

I don't know sorry

Not true

thanks guys!

TOTALLY unrelated question but, how much data will D2 go through if I were to tether my phone to my laptop for say.... 2 weeks?

Just try it for an hour, check your data usage then extrapolate.

I'm in a similar boat and my two week ban (if that's what it is) is up tonight. I've been using my personal hotspot (granted, I don't play a ton of D2) and it has been fine, no data issues.