Antonyms for the phrase "threw in to a tizzy" would be words that convey calmness, composure, and a steady state of mind. These antonyms could include words like relaxed, composed, tranquil, composed, peaceful, and unruffled. If someone were to use these antonyms in a sentence, it might sound like this: "Even though the news was troubling, she remained calm and composed, not thrown into a tizzy." These words can help to evoke a sense of control and peace, important qualities to strive for when we face challenging situations in life.