N.G.
Don't give them too many details, only things that they can understand, above all, TELL THEM WHAT THIS MEANS FOR THEM. Let them know that they will have two rooms, two houses to go to, and that Mommy & Daddy still love them both no matter what happens. Tell them the good things about it.
Believe it or not, I went through this as a child, and again as an adult, and it wasn't that hard when I was a child. It has been harder as an adult!! Kids are very adaptable, but they need things explained to them in a way that they can understand it without the drama & unnecessary details.