It's a police decision and then up to the prosecutor to charge. It sounds like both of you should have been charged.
My answer to you question does not constitute legal advice. Only an in person or telephone consultation will result in an attorney/client relationship. Please do not rely on brief answers without checking with an attorney in a confidential consultation.
Before I call it discrimination, I suggest you get an experienced attorney to represent you. The attorney can get a copy of the police reports/witness statements filed and review them for factual discrepancies. Additionally, a lot of police cars are equipped with cameras and recording devices, so your attorney should communicate immediately with the Oakland County Sheriff to determine if such tapes/recordings exist and, if so, that they be preserved.
Neil M. Colman
Mr. Colman is licensed to practice law in Michigan. The response herein is not legal advice and does not create an attorney/client relationship. The response is in the form of legal education and is intended to provide general information about the matter within the question. Oftentimes the question does not include significant and important facts and timelines that, if known, could significantly change the reply and make it unsuitable. Mr. Colman strongly advises the questioner to confer with an attorney in your state in order to ensure proper advice is received.