In Florida is a single member LLC considered a 3rd Party

I recently left a company as a partner and created a competing company that was filed as a single member LLC in Florida. Part of the separation included a non-disclosure agreement. There was no non-compete, no non-solicitation, or any other agreements. Simply a membership redemption contract and a non-disclosure agreement. Today I received a certified mail from my previous companies attorney stating that I had breached the non-disclosure by starting a competing business and disclosing information to a third party. I'm being told I violated the following: Contacting the current and/or former clients, Disclosing proprietary information I gained as an employee, and exposing trade secrets and other information belonging to my previous company. Considering the new business is just me I'm curious if my LLC is considered a 3rd party or if this is just a scare tactic to get me to close up shop. Thank you.