I'm sorry to hear of your troubles.
Before attempting to void the contract, have you considered assigning the contract? This might be especially easy to do if the construction that you purchased is sold out and/or the prices have gone up since you entered into a contract. Keeping the same terms in place, you might be able to find an eager investor who would be happy to assume your terms. You might even be able to proft, though right now I'm sure your main concern is just getting out alive.
Of course, to the developer this is considered "flipping". Depending upon the terms of your preconstruction contract, you may be able to assign your right to purchase the unit you chose before actually closing.
If the developer does not allow flipping, you can still sell your unit prior to closing, but you would have to do a double closing on the same day -- basically, you will close with the developer for your purchase, and then close with the new buyer simultaneously on the same day. There can be extra fees for this process, which is why flipping would be better for you. However, weighing that against potentially losing your deposit may be the lesser of 2 evils.
If you don't wish to try this route, without knowing the specifics of your contract, it is hard to say what, if any, penalties you would face. You might want to consult a real estate attorney to review the contract with you and see if there is any way out.