Andrew Hooper, 46, known as Jack, denies murdering Cheryl Hooper on January 26, in Newport, last year.
He is alleged to have shot 51-year-old Mrs Hooper in the neck and arm in front of her teenage daughter outside her home in Newport.
He then turned the unlicensed weapon on himself resulting in severe injuries which have left him unable to speak.
The shooting followed a confrontation at a pub while she was out with a group of friends including a man he accused her of having an affair with.
Giving evidence at his trial Hooper, who communicates using a keyboard, said he did not intend to pull the trigger on the side by side weapon and that he did not intend to “cause her really serious harm”.
The case so far:
Mr Philip Bradley, QC, defending, put to him: “In your prepared statement you told the police that “the gun somehow went off”. Were you there suggesting that the gun went off by accident?”
Hooper replied: “Yes.”
He told the jury that he drove to the public house, in Wolverhampton, to see who his estranged wife was with.
And he said that the fact that she was with the man “came as no great surprise” to him.
Mr Bradley further asked: “How did it make you feel?”
Hooper replied: “I felt anger at myself. And I felt disappointed towards Cheryl.”
Mr Bradley asked: “Did it make you feel sufficiently disappointed in Cheryl to make you want to kill her?”
Hooper replied: “No”.
He repeatedly told the court that he had only intended to scare his wife because he wanted her to come back home.
Hooper also revealed that three months passed before he found out that his wife had died.
Under cross-examination by Mr David Mason QC, prosecuting, Hooper said he wanted her to leave the man and give their “marriage a chance” and that he had been “wrong”.
Mr Mason asked him: “Why do you say you were wrong? The fact is you shot her dead so she was never going to leave (him) and come back to you, could she?”
Hooper replied: “I didn’t intend to hurt her.”
Hooper, of Guild Lane, Sutton, Newport is accused of shooting Mrs Hooper, 51, in front of her daughter despite previously signing over all his licensed guns to a friend after three suicide bids.
The jury has also previously heard that Mrs Hooper was not having an affair.
The trial continues at Birmingham Crown Court.