So I hadn't seen my friend for a while and but I've been sending her pins (especially Sherlock) and the first thing she does before I go over to her house is send me a pic of her and she captions it "Did you miss me?" I literally freaked out.
Sherlock season 3 episode My exact thought on why he told him. And my personal opinion that Sherlock would enjoy the irony of telling only ANDERSON of all people the truth of how he faked it. <--- i loved that that's who sherlock told
Sherlock has notecards! The extreme mega-mind that knows and remembers everything he has ever read/seen/heard and he has notecards so you can make sure he remembers because John is that important to him.