You may lose half of that plant but in the end, you could save it. Beside what everyone recommends, I would make sure the root ball is soaking up water into the center of it. You can do that by soaking it in a bucket for a little while. Additionally, while it soaks, you can fill the hole with water and let it drain down. That will baby it a little. Also was it rootbound? It may help to loosen up the root ball, ripping some apart if it is all roots and no soil wrapping around and around in a circle.
