I have a true story that was relayed to me in person from a friend of mine many years ago. He was involved with a celebrity at the time and they were on a trip to Paris and events there basically ended that relationship.

It's a basic human interest story about, personal identity, wealth and other themes. There are some other famous people involved in the perifpheral backstory that are meaningful in the sense that if they were removed, the story really wouldn't have any 'meat.' 

So my question, is, from a legal or ethical standard, how would I go about telling this story, keeping it mostly true (some of it would have to be fictionalized to keep the story moving and interesting). If I were to change the character's significantly so that they would not be recognized, they story would likely lose it's appeal. 

Also, when the story was relayed to me by my friend, it wasn't requested of me to no share it. 

I have since lost track of said friend so it would be difficult to get written permisson to tell the tale, and even so, he would not be authorized to release other personal interests from other parties in the story. 

It's a funny and strange little tale that I think would be a great short story. But being rather new to this and wanting to actually have this piece published one day. I am just not sure how to proceed.