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This book was published in the last decade, probably in the last five years. The story, if I remember correctly, takes place in the present - meaning when the book was published.
In one universe a few people survive in a timeline where the Cuban Missile crisis turned into full-scale war and the world was devastated. Somehow this universe 'bleeds' into our universe, just how I don't know.
I saw the book in a bookstore but I never read it. Does anyone know what this is?