Ex: Pistorius cheated on me with Reeva

Samantha Taylor broke down while testifying in the athlete’s murder trial in the Pretoria High Court.

Oscar Pistorius and Reeva Steenkamp at the SA Sports Awards on 4 November 2012. Picture: AFP.

PRETORIA - Athlete Oscar Pistorius's ex-girlfriend Samantha Taylor on Friday broke down while testifying in the North Gauteng High Court in Pretoria.

The Olympic and Paralympic athlete is in court for murdering his girlfriend Reeva Steenkamp at his Pretoria East home on Valentine's Day last year.

Reeva Rebecca Steenkamp. Picture: Carte Blanche.

Pistorius also faces gun-related charges.

The 27-year-old pleaded not guilty to all charges during his first court appearance on Monday.

Oscar Pistorius is escorted into High Court in Pretoria on day five of his murder trial on 7 March 2014. Picture: Sebabatso Mosamo/EWN.

Taylor broke down on the stand after telling the court that her relationship with Pistorius finally ended when he cheated on her.

"He cheated on me with Reeva Steenkamp," she told the court.

Taylor says she met the 'Blade Runner' when she was just 17-years-old and that their relationship developed over Facebook.

She said she broke off their relationship twice, first when he cheated on her with her best friend and then when he took Steenkamp to the SA Sports Awards.

Taylor denied claims the athlete went to bed with a firearm under his bed, saying when she was with him, he kept it on the bedside table.

The court had to be adjourned twice.

Taylor said Pistorius often got angry and anxious and had shouted at her and her friends several times.

Taylor was then asked if the athlete sounded like a woman when he shouted.

She said he sounded like a man.

In court on Monday, defence advocate Barry Roux said Pistorius sounded like a woman when he screamed because his voice pitched when he was anxious. He said he would call a witness to testify to that effect.

Taylor also outlined an occasion where Pistorius woke up after hearing a noise and thought his house had been broken into.

She said he woke her up before taking his gun and going to investigate.

Taylor also gave evidence about how Pistorius was pulled over by police for speeding on the way back from a trip to the Vaal in September 2012.

"After we left the policeman, Oscar was very angry at the time. I was sitting in the back [seat] and after that, they [Pistorius and friend] said they wanted to shoot a robot [traffic light]. About two minutes after that, I saw Oscar take his gun and shoot out of the car roof."

Get all the latest developments on the EWN Oscar Pistorius portal.

View the live blog and listen to live audio streaming from the trial.