Confront her softly about what you've found.

She walks in the door with some groceries. You watch her whispy, shoulder-length hair blow gently around her face as she steps inside. She smiles at you as you think of how much you love her, and just want to see her happy. At the same time, though, you are in disbelief she would have married you in the first place. You know you want to stay with her, but can't let her secret go on hidden now that you've found out.

"Honey," you say, "I...found something on the computer. In your email."

Her face goes pale and her smile fades. Something sinks into her stomach, knowing what you must have seen.