Check your state, but most are considered At-will employment. Basically, if you can not prove it by paper or hard evidence
LEGALLY, you got
NOTHING. I am not a lawyer and I am not saying you have nothing, rather trying to give you a scope of most people's employment agreement under the law. One thing you can do is write down EVERYTHING that happened with all the details you can remember like time, people, places etc. It is important to do this as soon as you have a chance to do so after calming down, because we tend to forget things more the longer we wait. In addition, maybe make a copy of this document and keep the original. Then mail the copy to yourself. The postal service stamps EVERYTHING and this can later serve in a court of law in many things,
while never opened. In closing, find a lawyer who specializes in this area and try to keep it all with him.
I hope and pray it all works out for you one or another! Some links below that may help.
At-will employment - Wikipedia, the free encyclopedia Employment At Will: What Does It Mean? History of At-Will Employment Law in the USA