1991 Toyota Corolla Overheated

Engine Cooling problem
1991 Toyota Corolla 4 cyl Manual 13500 miles

I was driving my car from Bunbury to Perth (approx 150 kms) and about half way there I noticed white smoke form the exhaust, and a dreadful noise form under the bonnet. Stupidly I had not kept an eye on my temp guage. It was in the red. I put it in nuetral and pulled off the road and it stalled itself. I waited half hour and tried it again, it started reluctantly but went straight back into the red. After coming back a few hours later I put water in it and it leaked straight out- quite quickly, I couldn't tell where from, but it seemed to be under the alternator area and definitely wasn't coming from any hoses. The plastic top of the radiator is also now cracked. Have I cracked the head gasket?