Brake lines are shot & underside of car is rusted. Is it worth fixing? on 1998 Buick Century

I have put over $3,000 in repairs. Driving home from repair shop a new problem arose. My brake lines were rusted thru and the underside of my car is rusted badly. I don't know if its worth fixing, or if I just lose all the money I have invested.

Asked by for the 1998 Buick Century