Water it every day and put it near sunlight (not too much) It might be too far gone. Depending how big it is, try taking it to a nursery and ask if it is too far gone. Luck
I understand that Remember, if the tree has lived it's life, be grateful that you had it's company for the time that you did. You don't have to throw it out either, bury it under a big beautiful flowering tree. It will hurt less with time, trust me.
I did have a xmas tree thaat we used every year. It was a real tree unlike the fake ones a lot buy. I loved the smell of it. Along from that, it's similar to when you lose a pet. Something that gives you peace and joy. It's obviously a sad thing, but you'll be okay