Abigail is stating that if David chooses not to take revenge he will have a clear conscience when Yahweh makes him king of Israel. This can be stated in positive form. Alternate translation: "You will always be glad you acted as you did-that you have not poured out innocent blood, or because my master did not attempt to rescue himself" (See: [[rc://en/ta/man/jit/figs-litotes]])
Abigail speaks of herself and David as if they are two other people, to show that she respects David. "you ... yourself ... you ... me" (See: [[rc://en/ta/man/jit/figs-pronouns]])