There are countless variations on that. I've always been partial to this one: Y es que en el mundo traidor nada hay verdad ni mentira; todo es segú

There are countless variations on that. I've always been partial to this one: Y es que en el mundo traidor nada hay verdad ni mentira; todo es según el color del cristal con que se mira which roughly translates to: "and it's that in this treacherous world, there is truth nor lie; everything has the color of the glass(es) through which we look", from Ramón de Campoamor, a 19th century Spanish poet.