This is tough one. And a good topic.
I reckon the hardest thing when you first learn that the watchtower is all bullshit is to keep your mouth shut. You are so amazed with what you learn that you just gotta tell your nearest and dearest.
I remember one rainy night my sister came over for dinner. I was just serving up the roast and we were enjoying some red wine when I blurted out that there was no need to worry about Armageddon because it was all a fairy tale. She put down her glass and her face turned pale. She said she had to leave, and she did. I gave her a plate of chicken and I have not ever seen her since. Or my plate either! That was in 1996. Up until then we had been extremely close.
So the point is be very careful and tactful how you broach this subject.