I have an 8 yr old too. She lives with her JW dad and step-mom. I am having a hard time knowing what to say to her also, I can't really go to into things with her yet, but I am trying to plant little seeds that will hopefully pave the way for some big conversations when she is older. One thing I wish I could do with her now though is get out the Bible story book, or the new book for kids and go to the page depicting Armegeddon. It is a horrific scene. Then I would ask her "do you think Jehovah would kill all these people.....people like (name people you know who aren't JW's)?" Then say "well....I didn't think so either. Tell her you found that the bible teaches something different than what the JW's were teaching.....and that you believe the bible over what some religion teaches. John 3:16 says EVERYONE who believes in him will not perish....I think that may help get her thinking in a different direction.
On a side note, when I was in therapy, I told my therapist that I wasn't sure what all to tell my daughter at only 8 years old, and she said it is the perfect time to be really straight up with them. So explain what you have learned about the organization and let her know that even though there are lots of people you love in the org still....you can't belong to a group that lies, and you can pary with her to help the people you love find their way out too.
I feel for you!! ((((((((((((((HUGS)))))))))))))))))))