My husband is incredibly controlling, to the point that even though I used our joint account card once, he took it away. I've used it once in nearly 30 years of marriage. There were quite often occasions when I had no money except for child benefit and that I had to take back birthday and Christmas presents just to get some cash. I've always scrimped and saved through necessity so that I could clothe my children in good quality second hand clothing and new shoes.
When I started working as soon as I feasibly could, it was so that I could treat the children in the school holidays by taking them to free places, taking a picnic and a kids meal from a burger chain on the way home. They were always so tired that it worked well as they'd fall asleep in the car after that, so it was a simple case of undressing, dressing in pjs, toothbrush and bed. It's really nice to know that they have no clue of what his behaviour was like and still is.
Also with that money it was expected that I buy all the family's Christmas presents, including his side, mine and the children's. Plus save enough to go on a cheap caravan holiday and home improvements. As for presents, I still bought him presents, but I always get IOU's every year. I've got a stack of them from him and now my son. For the first time last Christmas I turned tail and he got an IOU. Touché.
We aren't as well off as you, OverTheHammer, nowhere near, but were not starving. Not quite. Even when I went shopping, he'd question why the bill was so high. Thing is, I used to plan my menus and buy accordingly. I didn't buy non necessary items like wine or make extravagant meals. He has now taken that chore over, because he feels confident that he can do it more cheaply. It meant that I stepped back from the cooking too, as I didn't know what he had planned! He wouldn't write it down. I'd just shrug my shoulders when he came home from work. He's been known to leave me with one tin left in the cupboard. Usually soup! As a result of him now doing the cooking, even though he says "he only pays £65 a week, to feed a family of four adults", it's almost a certainty that he needs to go to the supermarket daily to pick something up, and returns with bags(plural). I've tried to get him to tot up just how much he does spend but isn't very forthcoming, so I've stepped right back. Some of his meals are foul though and that's not just me saying that😝.
After years of this neurotic behaviour I did actually want to leave him. I gained various qualifications, but was then struck down with a serious incurable illness. I have no choice now. I don't think moving out would be good for my health and I would have significant problems coping. Especially as he refuses to sell this house. I have absolutely nothing to fallback on, family wise. It's very frustrating to know how my life could have been...
In your shoes OverTheHammer, just explain to him the truth. It would only take him one five minute phone call, or even less, a glance at the website, for him to realise that you're not being straight with him. Then he'd develop mistrust in you forever more.
Instead, my approach would be to 'sell it to him'. Tell him that you feel really unfit since having the children and that you want to tone up. That you want to take pride in your figure so that he feels more attracted to you. Maybe say that It's been suggested by your GP as your blood pressure was a tad too high. Or that you want to lose a few pounds. I'd really 'sell' it to him. He'll have a fitter, more toned wife! Maybe mention that you were feeling a bit down and your GP recommended exercise as a way to lift that feeling as exercise produces more endorphins; the feel good hormone in your body. You'd be bound to have a bit more spring in your step, so it's not exactly a lie. Plus, he can't check up on you via your GP (patient confidentiality!) or a quick look on the internet.
That would be the route I'd take!
As for myself, I'll keep stashing away more money for that rainy day fund which I've already had to fall back on once through absolute necessity. I'll just leave His Nibs to carry on cooking😝. It's a good way to lose weight, looking on the bright side😉!