Pretty powerful leavingwt when you can put a face on the BS of the borg.
I think there are 2 types of Aha moments: Intellectual and emotional.
I think the intellectual recognition that this wasn't the truth probably comes first for most, based on what I read. (or at the very least, that uncomfortable "uh oh, what have I done" feeling when studying JW prophecy and eschatology)
It's the emotional though that can really move your ass out the door.
For me, my intellectual/emotional starting point was the same: the suicide of my brother. Having to come to grips with him being gay, and my turning a blind eye to his needs because of the cult was quite the head f*ck.
Then, little by little, the intellectual facade that they borg used came down, amazingly, because I took them up on their offer to study and understand more. Things like 607 BCE and 1914, anything they used to explain Revelation, having to justify disfellowshipping horny teens, having to deal with pedophiles in a less then honest and honorable way. All the damn sneaking around elders do.... And of course, being at Gilead where you are face to face with the BS dogma....
Emotionally though, I had one important piece still in, my ex. When I came to my own conclusion that she would never put me above the borg ever, that was all the emotional "aha" that I needed.
I love and miss all my old friends, but I couldn't live that lie anymore and lose what was left of the real me.