No, no, no, OP...we're approaching this from the wrong angle!
Endeavour to stay friends with her, come what may, for she may unwittingly provide much free and entertaining material. 
Unless you've already admitted details to the contrary, fob her off that, so far, you've just been MNing product reviews/ expert advice Q&As-type stuff.
However, you might now venture onto the chat boards...hmm, wonder what the other posters are like, you ask her.
You're sure they're harmless really. Probably give some sound advice...Maybe a few of them are even half-intelligent?
Commit her instant response to memory.
Everyone on this thread must similarly provoke the misguided MN-bashers in their lives into releasing their opinions/ preconceptions.
Results shall be compiled into a comprehensive spreadsheet and/or Venn diagram, the better to mock with our Viperish, judgemental, gin-swigging, Boden-wearing, Waitrose-shopping, feral children-raising, entitled children-raising, pearl-clutching and humourless ways.
With swears.
However, if she's fully aware you're in far, far too deep an active member, since The Admission, you can still get your kicks by testing whether she's elaborately double-bluffing you:
Casually include key giveaway MN phrases in conversations:
e.g. "Must go and fetch in the washing, before it's darked on..."
"Oh, good God, forgot to replace my Stunt Pineapple
(Allude to Buzzing Foofs and such, if she's edgy).
Observe closely. If any signs of amused recognition detected, no matter how fleeting or hastily disguised, she is already one of us .
And in denial.