InterestedOne, I can relate because I saw my ex-SIL go this way. When we met, before she became my SIL, she seemed a stong, independent lady with a nice sense of humour. We became friends as well as relatives. Before her marriage she was "studying the Bible" ( ) with the jw and soon after she was baptised.
It made for an impossible marriage. My brother could and did compromise, but a jw cannot. Also my friendship with her eroded as she only seemed interested in converting me. Finally she set the local jws onto me. With the current Apostate Angst, she has stopped communicating entirely.
This "friend" of yours does as she thinks she must. She cannot leave the religion out of it because she must "give a fine witness" but she must also panic at every logical response, as it threatens her cult personality.
It seems that you will have to part ways, but if you can, do it gently. She is trapped and cannot be reasonable, but she can still feel hurt.