Trustworthy - de confianza
You can tell her anything, she's very trustworthy.
Le puedes contar cualquier cosa, es de confianza.
dependable, reliable - worthy of reliance or trust; "a reliable source of information"; "a dependable worker"
faithful - steadfast in affection or allegiance; "years of faithful service"; "faithful employees"; "we do not doubt that England has a faithful patriot in the Lord Chancellor"
honest, honorable - not disposed to cheat or defraud; not deceptive or fraudulent; "honest lawyers"; "honest reporting"
responsible - worthy of or requiring responsibility or trust; or held accountable; "a responsible adult"; "responsible journalism"; "a responsible position"; "the captain is responsible for the ship's safety"; "the cabinet is responsible to the parliament"