Keep your head, lay off the brakes and let her roll to a stop. If you have to use brakes do it very, very gently. I have had a blow out on the Goldwing at highway speeds. (Hit a small piece of metal and it took out rear tire. Lost almost all air immediately.) Bear in mind some rear tires have a really stiff sidewall and will almost run flat, but tend to let the bike fishtail a bit. Had a flat on the Scarabeo 500 at about 50, but it went down slower. (Picked up a nail.)
I was with a friend in the Colorado Mountains on the Interstate about 125 miles west of Denver. At 70 in a long sweeper curve his rear tire on a 1500 Goldwing blew. He was pulling a trailer and riding 2 up. Bike fishtailed a little and he got her straight and coasted to side of the road. Tire was worn down to the cord and it blew a hole about the size of a quarter right in the center of the tire. He did a great job of controlling the bike. Note: There is a lesson in this one. We traveled a bit over 6400 miles that trip. When he left, the tire was in good shape but had a few miles on it. It wore out while we were on the trip and we were not checking tires as we should have been. Mine were worn enough that I ordered tires when I got home. I just replaced the rear tire on my Xciting 500 last week at 5100 miles. That trip was longer than the life I got out of the OEM tire. Keep that in mind on those long trips. We were talking as we were waiting for the service truck to get there. The day before we were running 70 and 75 up through Utah and outside of Vegas it was 107 F.
I am surprised the tire did not fail then. Guess we are not outrunning our guardian angel.
Don't take the chance check tires often on long trips, it can sneak up on you.