
First, I wanted to create situation compelling enough to make you turn the page. Infidelity is a scandal. Infidelity from the innocent spouse's point of view is a tragedy. Opening with that disaster, and conveying it through a cold, impersonal email lead into the second goal.
Second, I wanted to drop the the reader in the middle of that storm with Bobbi, letting you experience that off-balance feeling she has as she grapples the implications of that email. However, you as the reader know before Bobbi does, that her worst fears are about to be realized. Letting the reader in on that secret builds sympathy for Bobbi. Chuck is doomed before we ever meet him.
How did the opening work for you?