No matter what the outcome of your attempt to blow the whistle, you will be better off if you remain calm and only sound off to your family and friends--far from the work environment. Angry letters or outbursts make it easier for the company to believe they are justified in ignoring your complaints in the first place and make it more difficult for them to negotiate with you or your lawyer at a later date. No matter what happens to you in the workplace, go out with dignity. You can acquire a reputation as a problem employee from one emotion-driven tirade. Keep your head, and you can keep your pride even if you're ultimately forced to close this chapter of your working life.
The name of the game at this stage is strategy. You want to win this war and not just the first battle. Therefore, you must consider what is likely to hurt your chances and what is likely to help. If there is a particular supervisor you are sure is on your side, or someone else in top management who is friendly and aware of your good record, you could request a private meeting to explain what you want to do to keep working productively and why the company needs you on its team.