Assume nothing.
Please call those creditors and check the status of your accounts. You may find that many even though your name was on the application, you were only the authorized user and not joint, especially if he knew you were not legally married and was planning on defrauding you. The more legwork you do now to clear this up the less complicated things will be later and your divorce will cost less.
Get some accounts in your own name and keep them current.
On joint accounts, especially store accounts ask for a card in your own name a separate account, same for authorized accounts. Don't put any charges on joint accounts. Don't be tricked into putting charges on an account at the checkout for his charges because he dissapears at the last moment to use the restroom or some excuse. Use your card and or cash or check for your purchases, check for family purchases.
On any joint accounts, ask for your separate account A/O the date the Nunc pro Tunc was signed.
Request a copy of your credit histories from the 3 major credit companies, then compare that with what you find, then you will want all changes reported. Also report that there was fraud, but wait on that until you know the extent of everything.
If you have problems dealing with the individual creditors, ask immediately to speak to their fraud department, explain that your husband commited intentional fraud. He knew of the error on the divorce decree, intentionally lead you to believe that you were legally married when you were not and at the same time applied for credit etc. as married. When you discovered the error and the fraud, you immediately took measures to correct it, but you are not responsible for his debt or debt obtained by fraud in your name. Quote Ca. EC 623 as your source, you acted in good faith. If the IRS gets involved, you will claim "innocent spouse".
You do not own a home because of his fraud.
It is important to get all of his debt under his name.
Open a separate bank account for yourself if you don't have one already. Your worker's comp money is your separate income as is any settlement, DO NOT put it in a joint account, same for SSDI.
If you get divorced, you will still be entitled to the IRA/pensions from the corrected date of the final decree on the Nunc pro Tunc, but not the debt because of HIS fraud. You will be entitled to ask for spousal support and you will point out that he would not allow you to work making you totally dependent on him even though he knew you were not married and explain why you went to work and that you are now disabled.
Long term marriages vary from state to state and a judge may still award spousal support based on the facts so there is not a set entitlement for spousal support. If you get divorced, get an attorney in advance and be the one to file, that way your attorney who knows the judges in your area can challenge if needed. I know of some judges in an adjoining county who have had some investigations by the judicial council, others in other counties who will rule in favor of male batterer's against a disabled spouse and totally ignore fraud worse than what you are experiencing. While you cannot shop for a judge, it is important to be able to challenge one within 10 days under cccp 176 if there is reason to suspect bias. I don't know anything about the judges in your county.
If you get a divorce, ask for him to pay legal costs because of his fraud. Ask for spousal support. Also ask for post secondary child support for your child even though it is not normally awarded in California, the circumstances might warrant it. If he is making >$100k he can afford it.
Keep these posts as proof of when you learned of fraud and keep proof of how you attempted to correct the error including the incorrect advice you got.