And yet here you are having sent him 3500$ in 1 batch, I don't get it. 

Since Heisenberg63 violated a contract between him/her and OP, I think it'd be better if superme5 created a scammer flag ^{[type 2 or 3]} on Heisenberg63's account.
^{Note for OP: Once it becomes active, a red "trade with extreme caution" tag will appear on Heisenberg63's profile and there'll also be a "red banner" on top of all of his/her threads (for more information, refer to "Trust flags" thread).}

Have you ever dealt with him with such amount or previously deals were of small amounts? I think it was your own mistake to trust someone with such huge amount of money.

Instead of sending him that amount you could divide it into many deals so the loss could be somehow less than what you have lost currently.

I think something should be done against such scammers. A thread/megathread should be created for such scammers if there isn't one already and upon successful reports such members might get punished.

Damn, that's a lot of money and whatever @Heisenberg63 is doing now, pretty sure that's he's having a feast and all the debauchery using your money, you're easily shelling this much amount of money to people that you don't know on the Internet? You're one of a kind person to be able to do that and get no doubts about this person, you should've used some form of escrow for this one because that much money isn't something that you just give out so easily, hopefully you'd try to pursue some form of legal action because scammers like these person can't just keep getting away with it.

reading the chat you shared is frustrating, the dude is full of excuses.

you should have taken the negative tag seriously and looked for other people selling what he is selling or maybe bought the codes that you want from legitimate resellers.

anyway, he may(and hopefully) send the rest of the code that you bought from him, but what he is doing, like lying and making excuses, is unacceptable.

Did you already see this before you went into a deal with him, or was it after you felt you had been scammed that you did research on the profile? 
 
The guy in question had a few good reviews in the past for successfully dealing with others, but from the few reports, it appears that either he has lost his way or it's entirely a different person. His profile is already painted red, which is the best we can do from here.
 
Sorry for your loss. I will advise you to be more careful next time, or better yet, make use of an escrow to be on the safer side.