It sounds like you may have a justification defense based upon self defense. Pursuant Penal Law 35.15 a person may use physical force upon another person when and to the extent he or she reasonably believes such to be necessary to defend himself, herself or a third person from what he or she reasonably believes to be the use or imminent use of unlawful physical force by such other person. I suggest you remain silent and consult with an experienced criminal defense attorney who after reviewing all of the available evidence can provide you with a more definitive opinion.
You do not have to accept the ACD. You are presumed innocent. The State has the burden of proof. Speak with your attorney and decide after reviewing the discovery if you wish to go to trial or not. There may also be an issue of speedy trial which you should discuss with your attorney.
Note: For informational purposes only.