I've had what appears to be past life memories from a long time ago coming up, in which I was a mystic and then I willingly, deliberately, consciously, and horrifically betrayed the god I worshiped. He provided me with a vision of the future of my people, and rather than accept it, or ask him to change it, I turned to demonic forces; the results of which were, predictably, disastrous.

Is there an accepted method for what to do in these circumstances in order to apologize to the god?