You have few due process rights in this matter. Essentially, the commander will serve you a proposal of separation, and you have seven days to file a written rebuttal. You will get the free assistance of an attorney on base or you can retain civilian counsel at your own expense.
This post is for information purposes only and does not constitute legal advice, nor does it establish an attorney client relationship with Mr. Cassara.
Your best bet is to consult an experienced military law attorney who can help you prepare a strong rebuttal package and negotiate on your behalf with the Command. Most of the attorneys who respond to questions posted on Avvo offer free consultations. Take advantage of this service. Good luck.