it's true 10 years is a long time and no doubt saying good bye to your old job or clients is always hard and i think it's human nature, human get addicted to things which they do regularly and once they want to wrap them up then it creates bad feeling and it also create some open space in life but i think this is the reality of life, no one can do one thing forever, i hope after some days you will overcome these feeling, wish you all the best friend for all of your future endeavors! Stay blessed