A mature student told jurors she thought she was going to die when she was attacked by her ex-lover's wife.
Mrs Foster denies attempted murder
Cambridge Crown Court heard Julie Simpson, 44, was now blind in one eye after being repeatedly stabbed at Lucy Cavendish College, Cambridge.
The trial heard that Miss Simpson was stabbed 17 times in what the prosecution said was a "jealous rage".
Alethea Foster, 61, of Bromley, south east London, denies attempted murder and grievous bodily harm with intent.
Karim Khalil, prosecuting, said Miss Simpson, of Beckenham, south London, and Mrs Foster's husband John, a 58-year-old retired BBC political journalist, had been involved in a relationship for more than 15 years.
He said retired foot specialist Mrs Foster had become jealous and angry and had tried to kill Miss Simpson after arranging to meet her on 3 October 2005.
Miss Simpson told the jury she and Mr Foster had been lovers although in recent years the most exciting thing they had done was to "occasionally disagree about the answers to the Daily Telegraph crossword".
She told the court Mrs Foster had emailed her, asking to meet in her college room.
She said that during their meeting Mrs Foster "without warning" climbed out of the chair and punched her in the stomach, then attacked her with a knife.
Jurors heard Miss Simpson was stabbed 17 times
"She went down to the bag on the floor then she was up out of the chair and she hit me," said Miss Simpson. "It felt like a punch."
She said Mrs Foster was smiling. "She just looked very pleased with herself. Everything was gleeful really."
Miss Simpson said she managed to reach a corridor and call for help.
"I was quite tired and I couldn't breathe very well and I thought I was probably going to die in the corridor."
Mr Khalil said Mrs Foster had told detectives that she had not set out to harm or kill Miss Simpson but intended to kill herself in Miss Simpson's room.
But he said her actions and diary entries suggested she intended to kill Miss Simpson after meeting her at the college.
"It is plain from the diary entries that she sounds betrayed, humiliated and angry," said Mr Khalil.
"We say Alethea Foster plainly meant to kill Julie Simpson in what was a jealous rage against her husband's lover."
The case continues.