I'm sorry to hear about this.
I hope she pulls through!
Jet skis can be fun but I've heard of several people that have been badly hurt from them. While on Spring Break in the Bahamas a few years ago, my friend tried slowing down on her jet ski and wasn't able to control the ski. She was flew about 9 feet in the air and smacked her thigh back down on top of the jet ski. Her leg was badly broken. It's been 2 years and her leg is still bruised a nice purple color from the accident. Plus, sitting around in a Nassau hospital for about 5 hours wasn't the highlight of our Spring Break.
I'll keep your friend in my thoughts.