Intolerable: reading about other men's despair makes my despair more tolerable.
Great men's great despair against my measly little one.
A "loneliness that is experienced together" (Blanchot). And the observation, still by Blanchot, that whoever uses the phrase "I am alone" is necessarily comical.
I have no idea who first "used" the line "this loneliness won't leave me alone", but at least Otis Redding used it, before many others, such as the band Portishead.