AFFINITY (Spoilers!)

I just read the novel and watched the movie, and I am so heartbroken: Margaret is so unhappy, and then she is so cruelly manipulated!
Saying that, what would I do if I caught Selina?
Forgive her, of course; what else is there to do?
And, about the end of the movie: what does it mean? That the spirit of Selina saves Margaret?

God is subtle, but He is not malicious. (Albert Einstein)