how can i tell whether my little lemon tree is dead or not?

usually every winter it rarely snows here, but this year it was colder than the ones before. i have a little lemon tree i started growing 2 years ago. i have it planted in a big fat heavy ceramic garden vase. a couple of weeks ago the weather immediatly switched from humidy to freezing cold and it snowed. i had the little tree under one of those plastic tents but the stupid thing tore to pieces from the wind after a couple of weeks. a couple of days passed and i noticed the tree and its leaves were literally drying up, unlike the past winters and since i have little experience in taking care of these trees, i have no idea whether its dead or not. i just brought it in the house today, i live in a small apartment, theres barely any space, but i felt so bad for it.

the stems and small thin branches dont seem to snap, i cut off a piece and its still kinda green inside. its green leaves are still hanging, but in a dryish kinda deadish way. i have no idea what to expect. how can tell whether its dead, dieing, or alive??