Start with the recorded deed for the San Diego house. California Family Code section 760 generally treats property acquired during marriage, while a spouse is domiciled in California, as community property, except as otherwise provided by law. Read section 760.
That general rule does not answer every house-sale question. How the property was acquired, the deed, a divorce agreement or judgment, and any court order about the house can affect who needs to sign or what must happen before a sale. The title company reviews the documents to confirm the signatures needed for closing; a California family-law attorney can explain what a particular agreement or order means for you.
You can talk with us about the house while those documents are being reviewed. A written offer or sale conversation does not change a court order.