Now that I see your plans for this year and next, I believe that you have made a sensible and wise decision. The trip sounds like the chance of a lifetime, but putting long-time friends first is the best thing to do. There's nothing wrong with wallowing in nostalgia. After all, these are the people that shaped your life. They must be good people....one doesn't revisit bad memories out of nostalgia. You are very fortunate to have so many wonderful friends. It indicates that you must be a good person yourself.
You must have been to many places and seen many things. I just felt a sudden pang of envy, since I've also wanted to go look at the world, but haven't really seen much at all, compared with what I'd like to see. Circumstances always seemed to prevent any wandering that I contemplated, but the dreams were there.