There are whistle blower statutes that will protect you in this situation. You must tread lightly, but you simply cannot be fired for exposing your company's fraud.
Feel free to email me at firstname.lastname@example.org to discuss further.
You should consult an experienced labor and employment lawyer in your area about the situation with the employer.
Disclaimer: This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed.
You should consult an employment lawyer. We have a case now where our client disclosed the company's illegal activities to the district attorney and of course he is protected by the whistle blower statutes. I would not go around and telling your friends, their customers, or their competition but I would consult with a lawyer and/or report to law enforcement.