The rare statement by the double-amputee runner came ahead of the March 3 start of his trial for the killing of Reeva Steenkamp, who was shot in her boyfriend's bathroom in the pre-dawn hours of Valentine's Day last year.
Pistorius, who claims he mistook Ms Steenkamp for a dangerous night-time intruder, said: "No words can adequately capture my feelings about the devastating accident that has caused such heartache for everyone who truly loved - and continues to love Reeva.
"The pain and sadness -especially for Reeva's parents, family and friends consumes me with sorrow. The loss of Reeva and the complete trauma of that day, I will carry with me for the rest of my life."
The statement from Pistorius, 27, was unusual because his uncle, Arnold, has normally been quoted in statements from his camp, which has sought to shield the runner from intense media and public interest in a case that transfixed many people around the world.
Prosecutors allege the track star, who is out on bail, intentionally killed his girlfriend after an argument.
On Wednesday, a spokeswoman for Pistorius said he had reached a settlement with a woman over an alleged assault case from 2009. The woman claimed Pistorius had punched her.