I just bought this game retail off amazon and the fucking key has already been used. when I try activating it through steam it says its a duplicate key. Im so pissed right now. Is this is the shit we have to go through to play this game?

Pretty sure a key being already used has nothing to do with Steam, and everything to do with somebody stole the key. Ask Amazon/Steam.

Report it to Amazon. Amazon are brilliant with this sort of thing. If you tell them that something is wrong with your product they'll send you out a replacement right away. I once bought a retail steam game via them, there was an issue with the disk not installing. I had already activated the CD key because the start of the installation worked but about 5% into the instalation it crapped out. Since I'd used the CD key I thought Amazon would tell me they couldn't replace the disk and I'd be stuck and I'd have to download the rest of the game - and with my bandwidth limits that would have been a real nuisance. But I sent them an email asking if they could do anything and they sent a new one out immediately on next day delivery. It was fantastic. I mean, I could have easily been lying and just sold on that new copy of the game

And since any advice other than "Contact Steam support" or "Contact Amazon support" (both of which you've already been told) would involve circumnavigating Steamworks DRM, I'm locking this down. Providing instructions to break the DRM would promote piracy which is against our rules, so I'm going to lock it before anyone does that.