This all sounds like your relationship is poor, and you don't have each others backs. It seems like you don't really respect each other, and you just see him as someone who should be stepping up and providing for you and the kids no matter what.
You say you are a SAHM because that's what he prefers. What do you prefer? What do you want to do?
There's nothing wrong with being a SAHM if you are both on board with it. But it sounds like you don't trust him (and given the debt, I can understand that). But if you don't trust him, why in the world are you putting all your financial security in his hands. That's a huge risk for you, and a huge stress for him. How would divorcing help with this? You'd have no money at all, possibly not even child maintenance if he's quit his job!
You both need to sit down, discuss it, and have a plan going forward. No school fees is a given - you have a massive debt, and state school will be fine, especially at primary age. You need to get a job, even just part time, so that the money side of things doesn't all fall to him, and he needs to look for another job before quitting (unless his mental or physical health is at risk), while also helping with parenting. If it pays less, so be it, you will both have to just adjust.
I've been there (less the massive debt). I had 3 kids under 5 when my DH came home and said that he didn't want to go back to his job as it was stressing him out too much - he really hated it. I never questioned it, because if he hated it so much, who was I to say he had to go and do it for years to come. So he quit and served his months notice, then got some temporary work while he looked for something more permanent. I upped my hours at my part-time job, and set up a small home business. Eventually DH got a full time job on a fraction of what he had been paid before, but it meant that he was home more, so I could increase my home business. Yes, we had much less money overall than before, but our work/life balance was better, we both worked and also both parented. That was 20 years ago, and both of us being around for the kids growing up was the best thing that could have happened to us.