Robert Corbet has told his murder trial he truly regrets strangling Aoife Phelan.
The 25-year-old from Sheffield Cross, Portlaoise says he lost control and killed the Laois nanny during a row.
Corbet, who spent the day in the witness box, admits strangling Aoife Phelan in his garage and disposing of her body in a barrel on his family's lands in October 2012.
However he denies murdering her.
He says they were arguing and he lost self control and snapped after she threatened to ruin his life if he abandoned her while she was pregnant with his baby.
The jury has heard the 30-year-old nanny was not in fact pregnant.
Asked by the prosecution about the many lies he told Gardaí before admitting how he killed her, including a tale about dumping her body in a river, he replied that he was "afraid, he wanted to do away with himself" and that the "whole thing seemed surreal".
He said: "I've ruined families and lives because of this, it's something I truly regret."