If he dies without a will (intestate) you IMMEDIATELY lock up everything, head to the probate court and get yourself appointed representative of his estate. That puts you in control and the grown children get nothing until all his debts get paid. Whatever is left, if anything, can then be divided.

Under California intestate succession law you inherit ALL of the community property anyway and I'm guessing that the business is community property.

If he owns any separate property (assets in his own name) you get a share of that and the children get the rest.

You really need to talk to an estate planning or probate attorney. Even if your spouse doesn't want to, you need to educate yourself so you know what to do upon his death.