Legal Question in Family Law in California

It all depends on what happened to the money. There is no question based on the limited facts you provide that the balance on the credit card is a community debt, to be included in the equal division of debts upon divorce. The interesting part is where the money is now.

If she just spent the money she got for the reimbursements, you are out of luck. It doesn't matter whether she ran up $20k on business expenses and paid $20k cash for personal spending, or paid off the business expenses and ran up $20k in debt on personal spending. Plenty of guys find out upon divorce that their wives were running on deficit spending. Regardless of where the money came from and went, community cash in, community cash out plus debt accumulation to spend even more, equals net community debt.

If she kept the money and it is still around in an account somewhere, then the situation is simple. The debt is community debt, but the money is community assets. Since everything must be distributed so that it balances, if she wants to keep the cash, she gets the debt. Given her failure to manage money appropriately, however, if she doesn't actually pay the debt off, you are still liable as between you and the credit card company. So you should either opt for you to get the cash and the debt, or for an order that the debt be paid off before division of assets is confirmed (I did this in my own divorce where the ex was taking responsibility for a HELOC with a balance of $y that I wanted to make sure was closed, so our order said that I paid her $x, but that of that I could pay $y to the HELOC and close it, with the balance $z to her).

Where it gets most interesting is if she kept the money and has squirreled it away somewhere trying to keep it from you. If she has done that and you can prove it, the court has the power to award the money to you outside the property division. You would still be on the hook for half the debt, but all the money would be yours.