Can I get a DUI charge 7 months after the accident?

I got in a car accident on a rainy morning in December 2011. I hit a curb and my car was damaged very badly. No personal injury involved and I did not hit anyone/thing but a tree. My car was towed then, eventually totaled. I was immediately taken to the hospital by the paramedics. Police officers did not show up at the scene. When I arrived at the hospital, however, my blood was drawn and the result showed that I was badly intoxicated while I was driving. Police later showed up at the hospital to file a report. I did not tell them that I was intoxicated, but reported that I was fatigued/drowsy and the wet weather conditioned played a major part in the accident. Almost 8 months after the fact, I get a letter from the State of New York DMV asking to answer these three questions: 1. My description of the accident, 2. My physical condition before and after the accident, 3. Any other information which would explain the cause of the accident, because they are "investigating my involvement in the accident described above." Does this mean that my blood result was received by the DMV and that they're investigating possible DUI charges? If so, what is the immediate action that I should take in order to avoid getting the maximum penalty for the accident?