Zu meinem Schrecken stellte ich fest, dass ich mein Geld verloren hatte.

“Zu meinem Schrecken” here is translated “To my dismay” but this seems a bit mild relative to the German; Google translates it “to my horror”, and I think this is better.

“Schrecken” seems to connote schock and fear, both that something very bad has happened and that it is completely unexpected…whereas in English, “dismay” is milder on both ends, like it seems to connote that the event is both less serious, and less surprising, i.e. more of an inconvenience and perhaps something you might have even anticipated as a likely possibility.