That reads to me as less "evil" and more "unreflectively egoistic (with ego identity demands that are helplessly experienced as overwhelming and unstoppable), plus out of place (with malefic consequences)".

Maybe it would be good if she visited the tomb, and tried to think through what kinds of sacrifices traded away, in order for a place to be made for things in the world, would be worth it versus too destructive? I don't know, I tend to err in the direction of soft options.

I'm a little confused about who chose the tree and what significance they invested in the choice. It seems like that may be an important part of why things would have happened this way, if that was why.

I think obsessing spirits find it easier to puppeteer identity fractures in the person, taking shadow identities the person has dissociated off. Fixing the problem might involve working out what is going on there. (Wanting "the old me back" could be interpreted multiple ways, but it does remind me of the discussion in the book "Iron John" about the work that needs to be done to develop a coherent identity in adulthood, as this identity no longer comes easily the way a child's does.)