What sadness is?

Is it an emotion? Is it a fact? have experienced it at one time or another- in times of illness, loss, fear, stress, disappointment - as an emotional state brought on by circumstances. My life is on a perpetual edge of sadness.

I feel it lurking around every corner, crouching in the shadows. I wear sadness like a second skin, or at times I feel it sweeping over them like a suffocating wave. Even if I appear upbeat and happy, it is ...always present, a vaguely perceived mist in the distance.