John becomes addicted to drugs after Reichenbach
I'm searching for a fic I read on FFN. It was after Sherlock's "death", complete but rather short (I think it was only 2 chapters). John finds some cocaine (or possibly heroin) of Sherlock's and decides to use it to escape his grief, and eventually becomes addicted. He ends up homeless and out of work due to his drug habit. When Sherlock returns he is trying to find John but not having any luck. Then John sees Sherlock talking to one of his Homeless Network. Sherlock returns to the park John had seen him in earlier that day, and John thinks Sherlock has found him. So John goes to 221B and realizes that Sherlock isn't working on a new case, he's looking for John. Someone had left Sherlock a note saying he had missed something in the park earlier. John is too ashamed of what he has turned into and is going to leave when Sherlock comes in. Sherlock immediately figures out John has gotten into drugs but begs him not to leave. At some point in this conversation John is too afraid to look Sherlock in the face, but Sherlock basically sits down and hugs him around the knees (I think).
More details:
John, it is mentioned, is reduced to performing sex acts for his dealer for drugs--this is briefly touched on but not in detail. He refuses to sell drugs though.
I am pretty sure there was a sequel to the story as well.
Thank you in advance!