I'd be more worried about riding in the country on weekends. Those drivers are moving at a much greater speed than my commute, and they're less likely to expect a cyclist in their path.

My wife worries too. I've come to realize that if she's not worrying about my commute, then she's worrying about some other facet of my life. She's just a worrier by nature and has to channel it in some direction. I'll take reasonable steps to reduce her worries but I've accepted the fact that no matter what I do I'll be unable to remove every worry she has.