Don't give up, man; Similar situation here. From a legal perspective, you've goofed big time by admitting guilt and not demanding a lawyer immediately. From a moral perspective, however, you did the correct thing by owning up to your role in what happened and accepting the consequences.
I don't know you or your precise situation, but with me I was arrested on suspicion of criminal damage to property because some of my friends decided it would be cool to go and break things. They ended up being charged with burglary as well on a technicality.
As I have a tendency to be a bit pleonastic, I won't go into too much detail. Suffice to say I was cleared of any wrongdoing, though for a time I thought I was going to end up a felon for being a party to the crime. Even still I was now guilty of "toleration of those who do" by not immediately calling the police on those with whom I was associated.
The course of action I took was damage control and preemption. I informed my National Honors Society advisor, sports coaches, club advisors, etc in order to try to prove that I was still a man who valued the Honor Code and took responsibility for his actions and inactions.
I informed the RC and asked what I could do in order to help sort the whole issue out. At his behest I provided him will all relevant police and court documents and the contact information of the officer who arrested me.
I suspect the biggest deciding factor on what the outcome will be is the answer to this question: what happened and what did you learn?
Be completely truthful and point out where you screwed up as well as a few of the millions of courses of actions that you could have taken to avoid your particular predicament. Also find a way to spin it into a positive; for me, I was able to say I verbally attempted to stop what was occurring, I immediately told the officers what had occurred, and I told the truth even when I believed I was facing felony charges (no guns, no voting, no military service, jail time, etc) and it would put my friends in the same situation. I did my best to maintain my honor and maintain my moral character even though the consequences for doing so were dire.
Focus on getting ahead of what happened and create a helpful (TRUTHFUL!) narrative because in your interviews and correspondence with academy personnel they will beat you over the head with it and eat you alive. Remember: the correct answer is always some form of "no excuse, sir" when grilled about the whys and wherefores of what occurred.
They seem to have forgiven my stupidity, as I am now 3Q'd with two nominations. I am patiently awaiting a BFE; should it not arrive, I am convinced it would be due to my resume being insufficient rather than as a consequence of my arrest. That's not to say that they will overlook crime lightly.
Hopefully I helped a bit; my answer feels a bit disjointed and not so cogent...if i can provide any further assistance feel free to PM me--I know what it's like to be there.
Bear in mind that all 16-18 year old boys are idiots; some more than others, but idiots nonetheless.