In matters such as these, to trade, to sell or to keep, there is always one who benefits at the expense of another.
I say keep it.
You see, if you keep it, you won't lose any more money by selling it or trading it.
Further, by keeping it, you will effectively prevent any potential buyer from experiencing your concerns/worries, regrets and sense of loss. So why pass on the misery?
And should you actually profit from this potential trade/sale, then you'd be just as sneaky as the seller who gave you this misery in the first place.
Keeping it will be the most honorable thing.
-.-