Always be on the defensive - even in a car. A lot of folks out there are oblivious - they don't even see other vehicles, trees, brick walls, etc, let alone cyclists and pedestrians. I've been amazed in my couple of months of bike-commuting how many people are texting or fiddling with their phones in their laps while driving.

You should take comfort/pride in the fact that you were doing your part by being observant and saw the impending danger.