Jurors heard Ms Abbotts suffered more than 13 wounds to her head and more than 20 to other parts of her body.
Taking the stand for a second day, Mr Naseem, of Amersham, Buckinghamshire, recalled how Ms Abbotts had her hands around his neck and was choking him, and he was simply fighting back.
“A red mist may have descended over me,” he told the court.
“I think I may have lost my composure. I got out of that room as quickly as possible.”
Cross-examined by prosecution barrister Christopher Tehrani, Mr Naseem denied he had been under financial pressure and was facing mounting debts of at least £100,000.
He also denied he may have been irritated that Ms Abbotts was spending time – for which he was paying £2,000 per night – texting friends who were wishing her a happy 29th birthday.
Asked why after realising he had killed Ms Abbotts he had sent a text to his partner and mother of his two young children, Helen Jervis, that read “life isn’t going to work for me”, he said: “I don’t remember sending it… I was very upset about something.”
“Were you upset because you knew you had bludgeoned her to death?” Mr Tehrani asked.
“I knew she was dead,” replied Mr Naseem.
Summing up for the prosecution, Mr Tehrani said: “There was no red mist. Something happened to make you strike her more than 30 times on the head, leg, back, and neck.”
“It doesn’t sound like me,” replied Mr Naseem.
Ms Jervis told the court that her relationship with Mr Naseem had broken down some time ago, but she said he had never been violent to her and was a good father.