What is a friend?

My son got hurt at a friends house last night. I had to take him to the hospital.  He had blurred vision and pain. He was playing in their pool when he was hit in the face by a pool noodle. He is ok, he has scratches on his cornea. Someone was suppose to be watching the kids.  My son says he didn't see any adults there.  Not sure if they were there but not right at the pool.  But if you are watching the kids and you see kids hitting each other in the face, then an adult needs to say you can not do that.  My neighbor was not home when this happen and I was unable to reach her.  Her kids were there also.  What if something worst happen?  God forbid something happen to one of her kids and no one could get in touch with her.  Then to top off the whole evening she tried to say you know how your son can be.  If the situation was reversed I would be kissing her ass and offer to pay the bill.  Where is my so called friend when I needed her?