As for being a single parent that’s a whole other clusterfuck as I couldn’t afford our home, and i have no income atm. Dunno what I would do.
You need a plan for this. Hopefully not long term, but it's your sticking point right now. I empathise completely with it being hard; my parents are dead and whenever anything happens, I get asked why I don't go home. There isn't one to go to!
But you need a plan. A way that you'd be able to pay the mortgage for a bit, or somewhere to go. Could you increase your income via your business? Would you be entitled to help if he left? Entitledto.com is pretty good for benefit entitlements so you could run the calculator without him and see what position you'd be in.
Once it's clear in your head that this isn't your only option, you'll be in a better place. He is clearly a broken man and it does sound like he's in the midst of a breakdown, but he's refusing help and until he can engage with it, he's on a downward spiral and he's dragging you all down with him. Sometimes there is nothing else you can do but protect his children and hold everything together for him to possibly return to when he's finished self-destructing and starts to recover.
I would not be budging on him going to his parents for a few days at least. It would be hard, especially with a constipated toddler (and I second the glycerin suppositories suggestion!) but they have to be put first here and your husbands spiral will hurt them.
And I say this as both someone who remembers my mother's breakdowns from three onwards, and who has had one myself. You cannot make someone engage with help. You can't stop him destroying himself until HE wants to. He's not there yet.