she stresses "you know it's the truth"
That's par for the course. They think that just because they've had their 'minds cleansed' to believe that everyone else HAS to believe! I have a very good atheist friend and my wife still insists that 'he knows it's the tweth but doesn't want to accept it!' It's part of the brainwashing mind cleansing.
She has an answer for everything and for some reason i always come out looking & feeling like the stupid one.
JWs don't realise it but they are trained in the use of logical fallacies, hypnotic language and other propaganda tricks.
Just call them out on something that proves the GB are liars and you'll see her do mental gymnastics to prove the GB are infallible.
A calm analysis of what she says before replying would be best if you ever encounter her again. May I suggest you do what JWs are trained to do when asked a stumper of a question on the doors? They won't answer but will say they'll research it and return.
Write it down, post it here and we'll deconstruct it and identify the propaganda techniques used.
Also you might want to research 'logical fallacies' there are some excellent YouTube vids that explain how it works.
You won't win every battle in life but forewarned is forearmed.
Let us know how it goes. Stick with us!