Many claim that Sarah died of a broken heart or of anguish because her only
son was to be sacrificed. But this doesn't make sense. Sarah was a
prophetess. She didn't die from anguish, it was from joy. She died
because she knew that if her husband and son were willing to do such an act
(The Akeidah), than her job was complete. She had influenced and guided
Avraham and Yitzhak to the point where they had reached the level of
ultimate sacrifice for Hashem.
She died because there was nothing else she could possibly do beyond that
in the service of G-d. Part of her greatness was making sure that they
also received greatness.
News of the Akeidah killed her, but not in the way that most people think.