Mabeanie, the symptom known as 'rubber-necking' by the police, also applies to 'live' incidents shown on television.
Car drivers see a car crash on the other side of the motorway and 'rubber-neck' to have a good look at a tragedy as they drive passed on the other side of the road.
Similarly, anything closely resembling a 'live-tragedy' on television brings the voyeurs flocking to their screens.
Their only interest is in the fact that it was leonard and they knew you 'were there,' (erroneously) and that they could get some second hand 'buzz' by quizzing you about it. It hadn't registered with them that he was in Valencia when he collapsed and you and he were in Barcelona when he was as fit as a fiddle.
I'm afraid it's human nature.
Perhaps one or two of them will explore leonard's music/literature/history and who knows? Become new fans.
By the way, 18 months is a comparatively short term in 'obsession' terms when discussing leonard. You shall mellow with increased enjoyment, as time passes and leonard enters your life with more and more meaning. You will have to begin a 'collection' of CD's, DVD's and books, which will require the carpentry skills of a friendly cabinet maker, who will create a whole stack of shelves for your growing collection. Eventually you may posses all bootleg, foreign, obscure, international, national, and media regional performances done by leonard over decades. Your journey has only just begun...enjoy...
As for your friends and work colleagues, their loss.................................................................is their loss.

"Bipolar is a roller-coaster ride without a seat belt. One day you're flying with the fireworks; for the next month you're being scraped off the trolley" I said that.