Is this defamation or just unprofessional?

I manage a territory of distributors for a large corporation. I have had consistent challenges with one, where my female gender and younger age set me apart from the entire sales staff I deal with there. In the past six months the vice president has called my manager to tell him I am negative, but this feedback has not been received from any of the other 9 distributors I deal with. Most recently a local customer emailed that he had not received requested information from me (he had, but needed to be reminded). Instead of contacting me directly the distributor sent the email to my supervisor and copied the customer (not nice, but within their rights of course). I responded immediately to everyone (bad move, I should not have copied the customer) with the facts of the situation and a request for an appointment with the customer, the distributor, and myself.
The distributor responded to everyone (including my boss and the customer) that "as normal I have a condescending reply".
My question is: Is the above statement defamation or a statement of opinion? It seems to me he is presenting a fact to others (that I can prove is untrue with many witnesses) that damages my professional reputation.
I appreciate any help you can offer as I am trying to figure out my next steps.