You need to start from the principles in titchy’s post.
If he died tomorrow, what would happen?
As he is sole earner, is there hefty life insurance so that you have easily accessible money to survive?
Who would run the business so that your children could ultimately inherit it? If all the property is tied up in it (like a farm, say), how would the wages be paid etc.
Further on from that, when the children have left home or potentially inherit the business and its assets including your house, where will you live? And how will you survive without your own income?
Do you have a pension being paid into?
All these things need to be considered as if he could die tomorrow, but with a long-term eye to the future.
And yes, you need a will too, even if it feels like you have no assets.
In general though you need a longer-term plan around your own financial independence as being totally reliant on one wage earner who you feel you can’t easily discuss money with is not wise. Do you have plans to work outside the family business? If you’re not a part owner I’d be unwilling to put all my time into it.