You don’t want to make it like you’re giving him a to-do list, but more like, since you’re paying the bills now, he should lay down a foundation to be able to pay more bills later. (If you plan on having kids, maybe mention that — when you do, perhaps he will be doing most of the bill-paying for a couple of years while you are the one maintaining/growing your skills in the background; think of it like switching off over the course of a lifetime together.)
Hopefully, he’ll take to one of these suggestions.
These office sheds are a bit pricey to put outside a home that’s not yours. So … can your husband build you one? TWO PROBLEMS SOLVED AT ONCE.
Or, buy a used RV (see here and here for turning an RV into an office), and then you can sell it when you don’t need it anymore. Since you won’t really be putting any miles on it, it may not even lose that much value while you’re using it.
Speaking of which, can you work at the mom’s place while she’s at work? Or can your husband hang out there? She has a dining room table, right? Or does she have a shed or old barn or something that’s not being used, that could be turned into an office?
Whatever you decide to do, this isn’t really a situation in which your “wants” are equal (I “want” to work, and he wants to watch TV). Since you’re the only one working, your right to a suitable work environment is non-negotiable. I mean, I watch Mad Men. And stay-at-home wives don’t ever go to their husbands’ offices, turn on the TV, and watch true crime shows all day.
Good luck! Stay sane!