Will this be considered a legal letter of seperation?

My ex and I are getting a divorce and in NC we have to be separated for one full year. Once I moved out of our residence we tried to work things out but they didn't obviously... We had a letter of separation that we both agreed on and post dated for the day when I left and we both signed it and had it notarized. We are both trying to be agreeable in the separation and there is not any property or children that needed to be divided. I just want to make sure the Letter of Separation will be considered legal when I go to file for the divorce once the year is up...