1995 Other Jeep Models Head Gasket

This morming, very cold, My jeep started to overheat. My check engine light came on. I drove approximately a half mile and cut the engine off. Steam rolled from beneath. I assumed it was a stuck thermostat. My husband came back later and drove the jeep about a mile and a half to my work. He worked on it and got the thermostat to open, but he thinks there may be a blown head gasket. There was some water leak from the exhaust but did not appear to have any water in the oil when he checked it. Is it possible that I have a busted head gasket or could it simply be the thermostat. As I said it was cold this morning, and when he got it to running there was some steam and a little water from the exhaust.