If you truly feel that this dog is not right for you, then you should take her back.
Though, personally, I think you should keep her and get some professional help.
Of course this is completely your decision, but what if you take her back and she ends up in the wrong hands? Someone who ignores her issues.
Either way, I wish the best for you both.
Black/Tan, neutered male
"American Pet Line"
Varick vom Haus Jeffery
Dark Sable, intact male
DDR/West German Show Line