LOL...Relax, Annette...you didn't mess up that badly and you stopped before you ate the whole thing...good for you! 1/4 of a slice of bread has roughly 4 grams of carb, so it probably won't throw you out of ketosis. It could, however, cause some carb cravings so drink the water like everyone advised. It takes some time to unlearn old habits, doesn't it?