My dd was five. I told her that I was moving to a new house; that she'd see us both all the time; and that I didn't want to live with dad anymore because of all the screaming (or something like that, I don't rember exactly. it was definitely kid-friendly tho)
She freaked for about ten seconds, her only question was "who's going to cook dinner????????" in an agonized wail, then she was fine. She does NOT like going back and forth between houses, but I don't see any way around that, unfortunately. I did buy a house only 2 blocks from him though.