Oh, that is awful, I am so sorry to read this.
It is my worst nightmare and so upsetting and sad. You must be feeling devastated at the moment but I guess in time you may feel that at least Fletch was not suffering for long and though it is a terrible shock for you and very sudden, he was not in pain for a long time. Try and think of all the happy times you had with him and remember you did the best for him at the end. Take care of yourself and try not to feel too sad
Run free Fletch