The phrase "turned against" describes a situation where someone who was previously supportive or on your side has changed their allegiance. Some synonyms for this phrase include "betrayed," "abandoned," "defected," "rebelled," and "opposed." When someone betrays you, they have turned against you in a way that often feels like a personal attack. Someone who has abandoned you has left you in a difficult situation or no longer supports your cause. A person who defects leaves your group or organization, often for a cause they believe in more strongly. When someone rebels, they rise up against you and actively oppose your plans. Finally, someone who opposes you is actively against your ideas or plans, often coming up with their own agenda to push instead.