Gaslighting

How to respond to gaslighting?

"I heard" vs "You said"

"I heard you said" exercise. Wherever I'm faced with potential gaslighting, I just say what I heard. e.g. "I heard XYZ" the person might reply with "No, I said ABC! ..." I just calmly explain that "I'm not sure what you said, you might as well have said ABC, I just remember that I heard XYZ. How would you like to continue from here?"