Did I kill my van?

I (accidently) drove my van (automatic transmission) on the highway for about 25 miles with it in 3rd gear. Started smelling like it was overheating and could hear radiator sizzling. Then noticed I was loosing speed and tried giving it more gas and it just continued to slow down. Suddenly realized that I had it in the wrong gear so I put it in drive and it instantly died. I coasted to side of road and white steam was coming out under the hood. I tried to restart it and it cranked but would not start. It also sounded different when cranking, like a higher pitched sound than normal. Got a ride home, and husband went back with me a few hours later. It still won't start, just cranks. (He brought water to put in radiator, it was completely dry.
did I blow up the engine? Can it be fixed?