unhappy with friends

As I promised it Was good with excitment to me but my unlucky friend was running at neck-break speed that his left knee got pain, today I called him,his doctor says an MRI image needed to make decision about having surgery on his knee or just band it with chalk for weeks, im worry about him and i feel guilty :( i got feeling like it was fault of me that i brought up that begginer guy to the top of the slope,