i have read all the books. well, i'm reading the last one. & i don't remember stefan & elena really sleeping together like they did in the show (i know & i don't watch the show). i mean, if they did then i don't remember because i just remember more important details (i'm not s stefan/elena shipper that's why)& if they didn't then i'm damn right. but i just need confirmation :)

well they don't sleep together they exchanged blood, which btw is not the same. im not sure but i read or heard some where that vamps in the books cant have sex, but i think thats wrong. i'm not sure. anyway yeah they didn't have sex. they just exchanged blood. xoxo

they didn't because in The Shadow Souls Damon discoveres that she's a virgin yet, and she told him that. Hope I helped :)

elena is a virgin

Technically the answer is no.
Vampires cannot have sex in the book series.
However, they can exchange blood which essentially takes the place of sex for them and gives them the same pleasure.

yes they sleep together in the lst book the return

i dont really remember. but i thought that they had

MUAH!.. MUAH!.. YES OF COURSE THEY DID IN THE FIST BOOK!! DAMN!!

AND Sunbathe WHAT THE GUAM.. JAJAJAJA LOL.. THATS THE SERIES OF NIGHT OF HOUSE!! JAJAJA.. THEY DID HAVE SEX..