When Sherlock comes back he tells John that his suicide had just been a trick, but that's a lie. Moriarty HAD caught Sherlock by surprise, Sherlock HAD made the choice to die instead of seeing John get killed, and Sherlock really had died.

Mycroft or Molly (could see this either way) turned out to have some paranormal way of bringing him back, though, and Sherlock ended up having to go through with dismantling Moriarty's network. Except now, the whole time he's away, all he can think about is John and how he needed absolutely, positively zero time to consider before deciding to give his life for John's.