Sorry to hear about the accident! Get well soon, and from my own limited experience I may suggest not to "test" the healed part too early. I have done that and ended up prolonging my recovery, keeping me from getting back in the game as soon as I could have if I had just let my body complete the job.
Your disappointment at the likelihood of not being able to meet your friends at the end of the world is totally understandable and real. Somehow I believe that even if you miss the meet-up you will still enjoy the remainder of the trip, at least, that is what I hope happens. All the best to you both.