Explain to me the end of The Crippled God (obviously spoilers)

I thought i understood what was going on throughout most of the book. Retrieve the gods heart, rebuild him, free him by breaking the chains with the otataral dragon. I was right with the story right until the point were Cotillion stabs the crippled god in the back, and Fiddler thinks this is all part of the plan. What the hell? did they kill him to save the world from the jade statues about to destroy it? was all that compassion stuff just bs?