So the kids are fine which is great.
You need to take advantage of your situation. I'm a stay at home mum who also works so I know this is possible.
I still have time to do whatever I want because my child can always go to friends or family, which is good for her to do.
My husband works a lot because he has a valuable career. I do jobs from home to make money. You're getting gifts, flip them, use the profit to wholesale buy this week's most popular product on Amazon, then sell it at a premium on Amazon, undercut the best seller by a few pennies.
He's not taking much interest in what you do? Great, set up these side hustles, apply for remote jobs, and do them while the kids are at school. Housework doesn't take that long. My house is spotless and I home educate and work from home.
Don't sit around being miserable, instead build yourself a life; a social life, a working life, and I think it is a good idea to leave once the youngest turns 16 too. By which time you should have a bit of money, enough for a rent deposit, and work that will sustain you to pay that rent.
You're in a good position here, well placed to build something, not a bad one. Yes, it's bad emotionally but don't let it be; get out there and meet people and build a network.
There's a whole world out there. Being a SAHM does not stop you experiencing it, especially if kids are in school, you literally have over 5 hours to yourself each day. I don't have that routinely and I still get everything done and earn about £600 a month for myself.