To all the people on their high horses or the ones effectively saying, "well I have to work so why shouldn't you...?" -
Can't you see - the OP's husband has been quite happy for her to not work WHEN IT SUITED HIM.
You don't get to be facilitated by your wife for 15 years - never have to worry about your own children etc etc - and then the second the youngest gets to a certain age, click your fingers and declare it's time for your wife to get back to work!
No. Sorry, it doesn't work like that.
Why the f* should she now have to rush out into some boring, menial job? (Sorry OP, I don't know what you used to do)?
Men who want SAH wives don't get to have their cake and eat it.
It doesn't sound as if this family particularly need the money. The way the DH needs to be approaching this would be by having a conversation with his wife, ie -
"Thankyou for all you've done with my children and supporting me in my career. I realise this has taken a toll in your earning potential and of course I recognise you can't just step back in where you left off. How do you yourself see the next 10 / 20 years panning out? Is there anything you round like to do - maybe retraining or a business from home? What would you like to do beyond me snd the kids? How can I support you to get there..?"
This is the kind of conversation they should be having. He doesn't get to declare when and where she should be working at his convenience.
Some women on MN are worse than the misogynists they claim to despise, I swear to god.