Jezebel uses this negative rhetorical question to rebuke Ahab. It can be translated as a positive statement. Alternate translation: "You still rule the kingdom of Israel!" (See: [[rc://en/ta/man/translate/figs-rquestion]])
Here "heart" refers to the entire person and his emotions. Alternate translation: "be happy" or "cheer up" (See: [[rc://en/ta/man/translate/figs-synecdoche]])