Below you were wanting to know what is "an acceptable age for a child to be left alone at home sick while mom works". Obviously, your looking to nail your ex on anything you can "did not think of that angle" so you can get custody.
So if that is the game you're going to play...this YOUR behavior MUST be above reproach...because as I demostrated...TWO can play that game.
And let's be honest here...if it had been MOM and HER neighbor instead of YOU and YOUR neighbor...you'd be ALL over it like white on rice!