I think the key here for YOU is to figure out why you felt the need to respond at all.
Was it to point out she is a liar?
Was it to prove YOU know the truth?
Did you feel this was some how sticking up for yourself?
When we discover our why's on why we are reacting to them, we have a better chance of understanding ourselves and then the ability to make changes.
When I was dealing with an active addict it was very important to me to prove I was right, needed to validate my own intuition. Problem was, I was looking to the most damaged person for that instead of being comfortable just knowing it myself. I learned to turn towards healthier people for that. Like people here at SR and in al-alanon. Then it didn't Matt to me any more what the addict thought all that mattered was what I knew.