Vincent Tabak broke down in tears as he began telling a jury how he came to strangle Joanna Yeates.
Tabak paused and was unable to deliver his words as his barrister asked him about his relationship with girlfriend Tanja Morson.
Miss Yeates's family watched from the public gallery as Tabak gave his version of events for the first time in the witness box.
With his shoulders hunched, bespectacled Tabak spoke in a Dutch accent as he told how he met Miss Morson through internet dating.
Defence barrister William Clegg asked him if he had had any previous relationships. "No," Tabak replied.
Mr Clegg asked him about his activities in the build-up to Miss Yeates's death on December 17.
"I started to watch some television, made myself some dinner and had the beer," he said. Mr Clegg asked: "What did you have for supper?" Tabak, 33, replied: "I had a pizza."
The defendant said he then "decided to go to Asda to buy myself some small treats".
Tabak, who admits manslaughter but denies murder, said he thought he left his flat "within minutes" after sending Miss Morson a text message at 9.25pm saying: "Missing you loads. It's boring here without you. Vxx".
"I think I sent it before I decided to go to Asda," Tabak told the jury. "I took my usual route past Flat 1" - Miss Yeates's flat.