First we both felt that it was not very age appropriate, and my huge concern is that I didn't want him to internalize any statements, since kids his age are very egocentric he might think that since the world revolves around him that he did something to cause this change.
So we started off slowly explaining to him that Mommy and Leo were having new rooms built for them at Grandma's house. We started calling our shared home, the condo. And when he had questions, we answered them, always letting him know that in his new homes either mommy or daddy would be with him, we were not leaving him alone.
In my quest for explanation I found a book that was as straight forward and clear as our explanations. It is called "Two Homes", it follows a gender neutral child Alex as he explains that he has two homes. There is no mention of divorce, feelings, or struggles. Its very age appropriate and Leo really loves it. The first time we read it he had a huge smile on his face and said "Mommy, Alex it just like me, he has two homes!" Exactly the reaction I was hoping for!
So if you are going through something similar and are looking for a straightforward uncomplicated book for your kids you should check it out. We highly recommend it :)