Sounds pretty scary - it's never a good feeling when you hit that pedal and it just goes to the floor. I wonder what happened to your lines - they definitely shouldn't have worn out that quickly.
I've lost my brakes on the B190 twice now. Both times were hot days, I was towing a car, and I got into stop and go traffic on the DC Beltway. That's about as bad as it can get. (For those not familiar, "stop and go" on the beltway usually means 40 mph ->0 mph->40 mph->... and people jumping RIGHT in front of you no matter how fast or slow you go.)
When it happened the last time, I pulled off, came to a stop (using the tow dolly's brakes mostly), and waited about 20 minutes for the truck brakes to cool off. I could smell the brake fluid boiling. Not good, but after they cooled off they worked great again.
Today, my brother and I did a brake fluid flush. Basically I bought a large bottle (32 ounces) of DOT 4 fluid, and we opened each bleed screw and bled the fluid until it got pretty clear. It took us a couple hours, but I think it was well worth it - over time, brake fluid absorbs moisture, which lowers the boiling point of the fluid, thereby making them more likely to fail, and it rusts out the components to boot. I believe that fluid is the original fluid, too, because people rarely flush their brakes even though it's a fairly easy and cheap job to do.
The fluid we took out at first was as black as used oil. We got it to a light amber color. I feel pretty good that this work will pay huge dividends the next time I get into a bad situation...
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab