well i am not in any way and expert as i am dealing with my own citrus issues, but from what i have read is when a plant/tree has been inside for extended perios of time it needs to be hardened off again, by slowely re introducing it to the elements. i could be wrong and i am sure an expert will chime in, but i am at work and bored so i thought i would throw out my idea and see if i was right! :) i am sure it will bounce back for ya.

Unless the limbs are turning brown then leave them alone. No need to cut anything down. If they stay green give them a chance to come back. It may take awhile but they can still survive. I have a Oro Blanco that lost most of the leaves except for a handful at the bottom of the tree. It took 2 months but it finally had another growth flush and now looks great again.

Next: How often are you watering? What kind of mix is it in? How much sunlight is it getting since the move as compared to when it was inside?

And as many others here have stated...pictures are immensely valuable in getting the help you need.

Rob

if the branches are brown, prune them off. you said there were 3 lemons on one branch, if the lemons are still growing, then the tree should be ok.

i know theres been a few late cold fronts. did your temps drop below 40'F after you moved the tree outside?

If all the leaves are off, I'd pluck off those fruit immediately, too. Citrus naturally drop their fruit, but I've had my potted meyer hang on to a few dozen fruit the size of golf balls despite losing most of it's leaves. Once they hit a certain size, it won't easily give them up and may keep putting it's energy into them a little longer (but unlikely long enough to make them full sized). Needless to say, mine weren't good and I regretted keeping them there.