The phrase "gotten in to a dither" means to become agitated, nervous, or confused. Some antonyms for this phrase could be "calm", "composed", and "relaxed". Another antonym could be "unconcerned", which suggests a lack of anxiety or worry. Other antonyms could include "serene", "peaceful", and "tranquil". These words evoke a sense of peacefulness and calmness, which is the opposite of being in a troubled state of mind. Overall, there are many words that can be used as antonyms to describe the opposite of "gotten in to a dither", and they all suggest a sense of tranquility and calmness.