should have … to him/her
Tom debería haberle dicho la verdad a Mary.
Tom should have told Mary the truth.
Tom debería haberle pedido disculpas a Mary.
Tom should have apologized to Mary.
Tom no debería haberle hablado a Mary de John.
Tom shouldn't have told Mary about John.
Quizá debería haberle enseñado algo de lealtad.
Maybe I should have taught him some loyalty.