My DH is indeed great, he is the best man there ever was. (please don't all vomit at once )
It's much harder for you being by yourself, and it sounds like you don't get nearly as much support from extended family as we do. The people in my life who love & support me make a difference that money can't buy, and the food parcels always make such a difference, mainly because so much love and time goes into them (vegetables from FILs allotment, green tomato chutney, home made jam, eggs from my mum's ultra-free-range-borderline-feral hens) The lottery couldn't give me that stuff. When we want a holiday and can't afford to get up to DH's uncle we often have one at home - take sandwiches and orange squash to the park, walk to free attractions and back, stick a pin in our local page of the a-z and go to a street we've never walked down before just to explore.
I'm sorry you feel so low sometimes. You're doing brilliantly to be caring for three kids on your own and working as well. And it's great that you're doing a job you love - most people never bother to find something they love and take the trouble to do it well, so you're exceptional in that way as well. I can't give you any advice because I don't know your situation. But perhaps the trapped feeling will disappear when you least expect it - and it might not come as a lottery win but in some totally unexpected form. I hope so - I'm really sorry that you feel so sad.