Defamation/Non-compete/and wrongful termination

I was recently fired for "gross misconduct" for being insubordiant to an Operations Director hired as a consultant for my company. It was never communicated to me that he was my superior or that I report to him. I work in Healthcare sales for an insurance broker. I signed a non-compete 6 months into my employment in order to keep my job. I contacted a client I was supposed to meet with the same day of my termination, to say goodbye and to notify her that I was terminated and wouldn't be at the meeting that same day. My boss attended the meeting in my place with two company associates. The client stated to my ex-employer that she had heard of my termination and was upset because she enjoyed our working relationship. My x-boss verbally stated with three client witnesses, that he had to let me go because I was soliciting business outside of the company. This is untrue. I received notification from my ex-employer's attorney today (10/25) that they have knowledge that I sent an email to an existing client soliciting business, specifically naming the client I refer to above. The email they are referring to was sent on my personal AOL account from home, yet my AOL was loaded on my work computer and it appears they had accessed that for the "information" they claimed they learned. The email has mysteriously disappeared from my history. The client had never released information pertaining to receipt of an email to my ex-employer, and both my conversation and email was one of a goodbye, not solicitation. 4 days before my termination I accessed my internet history folder and had found that my ex-employer had loaded up my internet history folder with a myriad of websites I had never visited, I sent an email to my ex-employer on that date notifying them of the "error" and was told my password needed to be changed again. It's a complex situation because of the non-compete, I am sincerely interested in protecting my name (defamation), and how to proceed, I am required to respond to the "cease and desist" legal notice in 4 days and need representation. I am a licensed agent, and will be working on my own, so the defamation (the client said she would release a written statement of his conversation with them in this regard) and the obvious attempts at trying to frame me for internet abuse are my biggest interest, the wrongful termination for gross misconduct (inability to collect unemployment and COBRA benefits is also a concern) I know that NY is an at-will employer, but it is truly a hardship for me if I am unable to collect Unemployment. Please help.