Yes, I think the cold got it. 15 minutes in freezing weather will severely damage a tropical. But you had it in your apt happy and healthy for quite awhile, didn't you? I don't think different conditions in your friend's office would have affected it in 2 weeks - plants don't change acclimatization that quickly. I think there's a good chance it will recover. Just put it where you had it before, cut off the dead stuff, and take care of it as you were, though it may well use less water, so be sure to check the soil moisture between waterings. It should put out new growth in a few weeks. Let us know how it goes.