Husband reckless with our money

Husband and I have been together for 10 years. In that time he’s always gotten bored with where’s he’s working every two years and ups and moved jobs regardless of where it puts is financially. I’m currently a SAHM to two toddlers, one has autism and needs hours of intense therapy a day and the other is Sprech decayed so we also do intensive speech therapy three days a week. I’m responsible for all of this as well as keeping up our home doing laundry etc. I’m currently 24 weeks pregnant. My husband right now is making great money. We almost have enough saved to put a down payment on our dream house. He comes home today and says he’s not happy where he’s working any more and he’s starting a motorcycle store with his friend. He then says he’s going to use all the money we have saved for a house to put towards this business so we can have a “bright future”. He THEN tells me that he wants me to work there 4 days a week but we don’t have enough money for day care so I would have to take the kids with me while I work. So in short, he’s going to spend all our house down payment, I have to take our kids out of therapy in order to work there 4 days a weeks WITH three kids and when I tell him I have reservations he tells me that I dont work so I don’t have a say and I’m just not for it because I don’t want to get off my lazy butt and work in a business😡🤬 I’m enraged. He then answers the phone to his buddy while we’re discussing the situation and mentions how they’re going to go look at places for the store front TOMORROW (even though I just told him I’m not ok with this plan) and if hey find something they like they’re going to sign the lease on the spot. With no business plan. No capital. No product. Nothing. So now I’m crying in bed because he literally just destroyed our whole security as a family and when it fails (because IT WILL) we will have nothing to our name. What do I do here? Am I crazy for not being on board with this? I’m a SAHM because he insisted and now I had absolutely no say in where our money goes because I’m “not the one working”. Advice would be great because I can’t stop crying. I’m going to take the kids and go stay at my sisters tomorrow after the kids therapy because I can’t stand to even look at him right now.