The teenager accused of murdering 23-year-old mum Paige Gibson said he was “scared” when he fatally stabbed her in a corridor outside her Halifax flat.
The 16-year-old, who cannot be identified for legal reasons, made the claim as he was attacked by her partner minutes after the fatal early disturbance in June.
Aaron McIntosh told the murder trial jury that the teenager had knelt beside him as he tried to help his girlfriend and said he was sorry.
In a police interview on the day of the stabbing Mr McIntosh admitted that he “lost it” when he then launched an attack on boy as he claimed:”I was scared. I was scared”.
Mr McIntosh was captured on CCTV footage moments before carrying his fatally injured girlfriend along the corridor outside their flat at Weavers Brook in Cumberland Close before trying to save her life on a nearby landing.
Bradford Crown Court has heard how the teenager, who has denied the murder charge, and another youth had asked the couple if they could sell a tablet device and a mobile phone for them so they could get drugs.
The prosecution has alleged that the 16-year-old became angry after Miss Gibson returned without the items or the drugs and he later told a woman he was “gonna stab that bitch”.
In the police interview Mr McIntosh said the teenager was repeatedly knocking on the flat door and “whinging” about the £20 for his phone.
He described how Miss Gibson had pushed the defendant away and he had tried to pull the pair apart as they scuffled in the corridor.
“That’s when I noticed him with a knife in his hand,” he told police.
“I didn’t see him pull the knife out.
“I didn’t think he’d used the knife until I saw blood on the wall. I said you’ve stabbed her.”
Mr McIntosh said the teenager ran off downstairs and when he looked at Miss Gibson he didn’t see any blood on her, but then all of a sudden it started coming through her top.
He described how after punching and stamping on the teenager on the landing he had then started doing mouth-to-mouth and chest compressions with the help of a young woman who was on the phone to the emergency services.
Mr McIntosh said he had not seen the teenager stab his partner and there was no reason for him to go and get a knife.
During cross-examination by the teenager’s barrister Mr McIntosh accepted that he and Miss Gibson regularly smoked crack cocaine and that the boy had used the drug with them.
But he angrily rejected suggestions that he was himself a drug dealer or that he had been grooming the teenager as a “runner” for him.
Mr McIntosh insisted that the teenager had been using crack cocaine before he even knew him and denied an accusation that the couple had introduced him to the drug.
Barrister Christopher Tehrani QC, for the boy, made other serious allegations and also claimed that the youngster had been “under the grip” of McIntosh, but he vehemently rejected all the accusations
The trial continues