So sorry to hear of your loss. Although nothing can really ease the pain of losing a best friend other than time, I hope you might find some comfort in "Rainbow Bridge" http://www.petloss.com/poems/maingrp/rainbowb.htm
Maybe it's a bit too mushy, but read it, let the water rip , and think of Champ. You'll see him there, through your tears and he'll be smiling back at you, and there's no better comfort than that! Happy memories last forever!