Sorry to hear about that Tom. I hope she recovers. I have been hit 3 times by cars myself... the last one put me into the hospital and changed my view on cycling, but I still do it.

As far as riding with traffic... the idea is that motorists are supposed to look and be aware of what is in front of them. That drivers are supposed to "give way" to objects/obstacles in front of them and thus a cyclist should worry the least about what is behind. The actual statistics gathered over a few years and from really too scant data show that most collisions involve intersections and crossing situations, not overtaking (coming from the rear) situations. HOWEVER, the most deadly collisions are those from behind, as they tend to be high speed, and the cyclist is often not aware of what is about to happen, so no evasive action is taken.

Further, when riding with the flow of traffic, one is supposed to be visible to turning and merging motorists, who are looking at oncoming traffic (the direction you would be going, as you flow with traffic) vice looking the other way. If you ever take long walks and walk against the flow of traffic, you will notice that motorists rarely look to the right, they tend to look to the left, into the stream of oncoming traffic. Also the combined speeds of riding into traffic make the collision energy much higher.

Of course at speeds over about 30MPH the survivability rate of a person in a person/auto collision goes down dramatically.

Yes, I would love to ride separate paths... but I don't expect to have a path going to every location I can ride to anytime in my life. I bike commuted for years and used the roads just like a slow motorcycle... I even lived without a car for about 7 years. I still enjoy cycling, but these days, I keep to paths as much as possible... there are too many cell phone/fast food/GPS/radio/TV distracted motorists driving far too fast for my comfort. So these days I tend to follow a "Rule 9" mentality and work to stay out of the way of the automobiles.