Criminal Law Questions? Ask a Criminal Lawyer.
Ok. You made a rash decision and a mistake. Go see a local criminal defense attorney tomorrow. Do not wait. There may be something he/she can do to turn this around and it will be well worth it to prevent being charged with a crime (federal and state possibilities here).
Do not talk to anyone else about this... do not do anything else. Go see a lawyer first thing tomorrow. Sorry I can't help you anymore than this, but it could be serious and you need to make every effort to correct things immediately.
I am not your attorney. This forum is for general questions and answers and I cannot provide you with applicable law or legal opinions or advice in your jurisdiction. Please seek the advice of a competent attorney in your jurisdiction. While I can answer general questions and discuss general legal principles, I cannot give you legal advice in your state. The internet is a great place to get general information but should not be seen as a substitute for the attorney-client relationship or the services of a good lawyer in your state.
You may be able to have your attorney make contact with the company that issued the check. You may be able to have your attorney make contact with the bank to stop the check from processing. Your attorney may also have other ideas on how to stop this from continuing, or you may simply be advised to immediately send the money to the issuing company and ask them to reissue the check. The possibilities to disarm this bomb are endless but you need to make every effort with your attorney to get this fixed now.