As long as the temps did not drop below freezing I doubt, the outside weather hurt your tree. It was more then likely the abrupt switch to the new climate inside you home. Plants are very conservitive by nature, and don't take to changes too well. It is more then likely a state of shock that is making your plant drop its leaves and fruit. A orange tree takes a LOT of light. If you can not provide natural light for it, the try getting a grow light, and keeping it in that for the normal day light hours. The other thing That I am not sure of is how a orange tree would work this far north and inside. It may loose its leaves, just as many other trees do. I have never had one so I could not help yo with that from my own experience. What you could look for however is to see if there are new leaf buds that have formed where the old leaves fell off. These would just look like little tiny nodes protruding from the stem.
Next season to try to save the fruit, bring the tree in while the conditions are simular outside and in. that way you won't have to worry about shock as much. Just remember that the air outside is usually much more damp then inside so a humidifer or misting will be in order.

Hope this helps you out

Mike

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