The value is the value, not what the owner paid or owes on the vehicle. Check to see if driver's insurance company obtained a full signed release for any and all property damages.
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.
The "total cost of loss" is going to be the fair market value, since by definition the FMV will allow you to purchase a comparable replacement vehicle. Either way, you still owe the 19k, so that is not a "loss."
This answer is a general interpretation of the law and is not fact specific to your case. Likewise it does not create an attorney-client relationship. You should seek an attorney for a review of your specific facts and documents.
Mr. Crosner's advice to "Check to see if driver's insurance company obtained a full signed release for any and all property damages." is very good advice. If so, nothing further is owed.
Mr. Crosner is licensed to practice law in California and has been practicing law in California since 1978. The response herein is general legal and business analysis.. It is not intended nor construed to be "legal advice" but rather it is analysis, and different lawyers may analyze this matter differently, especially if there are additional facts not reflected in the question. Oftentimes the question does not include significant and important facts and timelines that, if known, could significantly change the reply and make it unsuitable. I am not your attorney until retained by a written retainer agreement signed by both of us. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.