I agree with optimist Jackie. I think it is in the best interest of the children that you (and your H) have a talk with them BEFORE the trip.
My W and I never had a talk with Solomon. I tried to explain things the best that I could to a 5 year old. I didnt think that W would be able to do that. A few weeks ago, he must have heard the word "Divorce" at school. He came home and got pretty upset with my XW that we were getting a D. I had explained everything to him before this, but never used the D word.
The little bit of pain that it will cause in the beginning, will be much less than it would be if you let them figure it out on their own.
Just my .02.
(((((Jackie)))))
FLoyd The grass is always GREENER over the septic tank.