God's jealousy and anger are not sinful because jealousy and anger are not inherently sinful — only their corrupt expressions in fallen humans are.

Galatians 5 lists jealousy and fits of anger as works of the flesh. Ephesians 4:26 says "be angry and do not sin" — the same author (Paul) shows that anger per se is not always sinful. Righteous jealousy exists: a spouse whose partner has been unfaithful has an appropriate jealousy; that is different from coveting someone who belongs to another. God's jealousy over the exclusive devotion he is owed is perfectly proportional and holy. Fallen humans are especially dangerous when angry because we quickly cross into sin; God's anger is always perfect, appropriate, and proportional. James 1 is cited: the wrath of man does not produce God's righteousness.