I think a lot of posters are filling in a lot of blanks. Who knows what has been agreed in the past about the OP going back to work. Maybe they had agreed that she would go back when the baby was 12 months so he could take a lower paying job that didn't require him to work away? Maybe not.
But I agree with VicPark and RL&P that there's more to this. The email was wrong but I'm reserving my views on everything else.