It always seems darkest, just before it goes pitch black.
"It's even worse than it appears / but it's alright"
- Garcia / Hunter
A similar quote I remember: "Nothing is ever as good, or as bad, as it first appears." I don't have a source for it; it may even be a misremembered version of a misquoted version of that quote.
Maybe you're thinking of Hamlet's "There's nothing good or bad but thinking makes it so." ?