I am an avid bike rider, but I also used to drive a delivery truck. I say that this was the biker's fault, not yours. Bikers need to be aware of traffic, more aware than cars. If 2 cars hit each other, a lot of the time the damage is simply monetary. When a biker goes down, there is almost always blood involved. Riding against traffic, too fast on sidewalks, things like this drive me nuts.