Hun, posting art that isn't yours on here is stealing. You can't cover up what you did by leaving it on here and blocking those who comment telling you so. The way I see it is you have really only 3 logical choices.
You can either:
A. Take down the stolen piece and start drawing your own art. (Easy as pie)
B. Take down the stolen piece and deactivate your account. (Which I'd rather you didn't deactivate, dA is a wonderful place to share art that YOU yourself created and learn to improve your art. It's not that hard to jump back on the horse, just don't sit on it the wrong way. I even have a friend who made the same mistake, and now she's posting her own art and has her own watchers.)
C. Continue trying to hide. (Everyone has already reported you, so you'll just end up banned by the staff. fyi: they can still report even when blocked.)