I hope Tulpa gets exorcised. I do not wish for the death of the world, as then no one gets complete enlightenment, only oblivion, instead of a grand release its more of a screaming death of being absorbed to be used as a energy source.
As far as the groups choice.... I hope Berg can find a way to let go, maybe not to her death or worse, but let her go to live her path and his. By being together its a warped relationship influences by a lower soul that no longer exists. For both their sake, he needs to let go, that's why the Mara could hurt him through her, because he is attached. As hard as it is, he needs to, to save them both.
If Berg had let go in the first place, she would not have been in danger in her new life to begin with.