There are a number of antonyms for the phrase "am cahoots with," which means to be in league with or collaborating with someone or something. Some possible antonyms might include "opposed to," "competing with," "estranged from," "antagonistic toward," or "dismissing." These words all suggest that there is some sort of conflict, tension, or disagreement between the speaker and the person, group, or idea in question. They can be used to express a wide range of emotions, from mild annoyance or skepticism to outright aggression or hostility. Whatever the context, these antonyms remind us that human relationships are complex and multifaceted, and that we must always be mindful of the power dynamics that underlie them.