Maria, because you haven't been baptised, The Watchtower has no authority over you.
YOU have nothing to fear by telling your JW study-buddies "I have seen enough to conclude that you are a CULT, and I don't want anything to do with your so-called religion. Those YOU call "apostates" are correct."
IF you did that, especially the part about agreeing with "apostates," you will probably never see those people again, and it is possible your address will be avoided by JWs in the future. You might also plant a seed of doubt in the minds of you "Bible" study conductors. "What did SHE see that WE can't see?" they might ask.
But you are in charge of you, so do what you feel is best.
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Listener suggested, "You could get the JW a small gift and thank them for the studies that you have had together. Explain that you've gone as far as you are happy with and don't feel you would get anything out of studying any further. By giving a gift you allow yourself to feel less guilty and your kindness makes easier when you meet in public."
Yeah, something like a vacation home in Hawaii , for example. That would be nice. You could give them the Paradise they dream of, and they wouldn't have to wait for Jehovah's cloud of anti-matter to kill the current occupants of any Hawaiian estate!