S2 E2: The Time of the Ghost
"People write stories pretending you can alter the past, but it can't be done. All you can do to the past is remember it wrong or interpret it differently."
The horrors of the past, the traps of the future, and being cursed, with sisters.
[NB: this is another one that deals more directly with abuse and suicidality in several forms]
For more on Time of the Ghost, check out Em's Reactor article on Making the Metaphor Literal: Fantastic Reality in The Time of the Ghost by Diana Wynne Jones.