UGH, I don't look forward to telling my girls anything.
The therapist I see says that luckily they are younger and with our schedule (they are used to us being alone with them. One works, the other has them), I can do this in phases. They probably won't even notice if H moved out, honestly. He will be around when they are awake for the most part, and he leaves before they wake up in the morning for work, so they are used to that.
It seems you guys can do this sort of phasing too.
But I don't want to look them in the eye and teach them what the word "divorce" means.