Underbody Shield problems of the 2000 Honda Passport

I took my car to a mechanic last week because I was having to put brake fluid in it. I thought maybe I had a leak. The mechanic called me back and said I wouldn't drive that car anymore. It has excessive corrosion underneath. The frame is broke at least in one spot and the back is about to break into and come up through the floorboard. This is my only vehicle and I have to drive it. I don't know what to do. I just can't understand. I know that I live in a somewhat wintry area, but I am fanatical about keeping my car cleaned. The vehicle is only 12 years old. My husband has a Subaru that's almost 20 years old and has 272000 miles on it. Its no where near rusted like mine. I know that there was a recall on 2001-2002 Honda Passports for this reason but year 2000 wasn't involved in that. I definitely think that it should have been. You would never believe my undercarriage unless you look at it. Please help me to get some kind of help with this issue. I found a forum online and there is a lot more people with this same problem.