Who said "I am the only witness. I am the only one who knows."?

This quote is attributed to Rachel Watson.

I am the only witness. I am the only one who knows. - Rachel Watson

"I am the only witness. I am the only one who knows."

Rachel Watson Truth

Character in The Girl on the Train

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"I have lost control over everything, even the places in my head."

"Every day I take the same route, I see the same things."

"I'm nobody. I'm nothing. I don't exist."

"The thing about being really, truly alone is that you don't even feel it at first."

"Lucy, you got some 'splainin' to do!"

"You must always be honest with the people you love."

"Truth always comes out in the end."

"Honesty is always the best policy."