Mr Ashford, 18, told the jury how on April 30, he went for a night out with Emily and others before they stayed the night at the house of friend Oliver George.
Turner had been in conversation by text message with Mr Ashford that night.
The court heard Turner texted Mr Ashford: "What's been happening? You're my best pal, tell me why the f*** my bird left with you?
"Did she say anything? Man I'm trusting you."
Mr Ashford replied: "I'm trying to get to sleep."
However, it emerged Mr Ashford had sex with Emily that night.
Under cross examination by Turner's lawyer, Anthony Donne, QC, Mr Ashford admitted they had spent the night in Mr George's spare bedroom.
Mr Donne asked the teenager if he had sexual intercourse with Emily that night.
Mr Ashford said: "Yes."
Mr Ashford also told the court: "On the night of Emily's death, Turner told me, 'That bitch is going down tonight.' He seemed annoyed.
"When we arrived at Cafe Shore later on, Emily and Turner were not talking.
"After arguing for a while, though, she threw her drink over him and shouted that she did not want to be with him.
"She said, 'I hate you, I never want to see you,' and called him a freak.
"She then left the bar and Elliot started punching the sides of the booth we were sitting in and was screaming.
"He said, 'I will kill her. I will go to prison for it and still be a millionaire. I would do 10 years, it wouldn't bother me'."
ACCUSED JOKED ABOUT MURDERING EMILY
The court heard that the day before Emily's death, Turner shocked friends by pretending he had 'murdered her' and giving them a graphic description.
Turner told two teenagers he had smashed Emily over the head seven times with a lump hammer until he 'heard her skull crunch'.
Jasmin Snook, 19, told the jury she burst into tears when she was taken in by Turner's lie in the early hours of May 6 after a night at club Klute.
Miss Snook said: "In the early hours of May 6 after a night out in Klute, Turner texted me to say he had done something stupid.
"He said he needed to speak to me face to face.
"He turned up at my house about 3.05am and I went outside and talked to him on the pavement.
"He was near tears. He said 'I need to tell you something, I do not know how to say this'.
"He said 'she is dead'. He then started crying hysterically."
Miss Snook said that one of Turner's friends, Oliver George, then turned up.
She added: "Turner told Oliver 'she is f******g dead, I killed her, I smashed her seven times over the head with a mallet.
"'I heard her skull crunch.'
"He said it happened outside Klute in the car park and he threw her body in the bushes outside.
"He said he had his passport and had five grand in cash. He said he was going to write a letter to his parents and just get out of there.
"Turner was still crying, saying 'Emily is never going to have a family, she pushed me into it'.
"He then burst out laughing and said 'I'm f******g joking'."
Miss Snook said that Turner's friend Tom Crowe then turned up and Turner
said: "Emily is safe at home sleeping - but in a parallel universe I would've killed her."
Miss Snook added: "I then burst out crying.
"I got back in my house at about 4.30am. I had a Facebook notification from Tom Crowe which was titled 'Dead'.
"It said 'Emily's body has just been taken past Klute in an ambulance.
What the f**k did Elliot do?'
"I replied 'that is not funny, I feel really sick'."
The trial continues on Monday.
