There are a lot of assumptions being made here about what the OP *ight* have done. Unfortunately, the OP seems to be refusing to provide the information that is requested to assist them, and the information that they are providing doesn't make any sense.
OP says:
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I created an address in the "Addresses" tab of bitcoin-qt
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I don't think there is a way to create addresses in the "Addresses" tab (in Mac OSX, there isn't even an "Addresses" tab, there is only an "Address Book" tab).
If the OP used the "Address Book" tab, then the client does not create an address, but it does let you enter an address from scratch.
It will not however let you enter an invalid address. Therefore, if the OP actually did enter an address into their address book, then they have to have gotten a valid address "from somewhere" to have been able to enter it there.
That brings us back to the question of what address did they enter, and where did they get it from.
It *might* still be possible to get the bitcoins back, if the OP would just cooperate and answer some simple questions.