When Demetrius thus lost his power and fled for refuge to Cassandreia, his wife Phila was full of grief and could not endure to see her husband, that most afflicted of kings, once more in private station and in exile; she gave up all hope, and in hatred of his fortune, which was more secure in adversity than in prosperity, she drank poison and died.
Edition :
Plutarch. Plutarch's Lives. with an English Translation by. Bernadotte Perrin. Cambridge, MA. Harvard University Press. London. William Heinemann Ltd. 1920. 9.
Remark :
perpetrator: Perpetrator and victim are the same because it is a suicide. date: The date is taken from the New Pauly.
http://referenceworks.brillonline.com/entries/brill-s-new-pauly/demetrius-e314200
It is only an approximation since we do not know how long it took for the message to reach her.