A mother accused of causing or allowing the death of her three-week-old son has told a court she would "never lay a finger on him".
Roxanne Davis, 30, from Gosport, said she "had my whole world in my hands" when Stanley was born.
Jurors have heard Stanley had suffered 41 fractures to his ribs, arms and legs by the time of a fatal head injury.
Ms Davis and her ex-partner Sam Davies, who is not the baby's father, have both denied causing or allowing his death.
Winchester Crown Court has heard 24-day-old Stanley died of a skull fracture and brain haemorrhage on 28 March last year.
Jurors have heard from an expert who said the baby's fatal injury was probably inflicted on 19 or 20 March.
"I think it happened when me and him [Mr Davies] had an argument," Ms Davis told the court.
"He [Mr Davies] must have got angry and done something... when I was in the bath, down the shop, smoking, when I'm asleep."
Her barrister, Katy Thorne QC, said it would probably be suggested in court that Ms Davis hurt her baby when she was depressed.
"I would say that's stupid," the defendant replied. "What mother would hurt their own baby?"
Ms Davis, of Lee Road, wept through her testimony.
She told jurors she was "over the moon" when Stanley was born but admitted she did not know who his father was, because she had been sleeping with two men at the time and been told by a doctor she could not conceive.
Ms Davis was already pregnant when she met Mr Davies.
After Stanley's birth she had at first suspected other family members accidentally hurt her son by "holding him wrong", she told the court.
She told the jury she had a number of physical issues after birth, and as a result Mr Davies often got up with Stanley in the night.
"He would say he would get up so I didn't have to," she said.
"I didn't hear [Stanley]...I was really tired, my body was drained."
Ms Davis admitted having heated arguments with Mr Davies during which she threw things around their flat at Garland Court in Forton Road, Gosport, including an ornament, a metal baby bottle steriliser and a bottle of drink.
She also accepted using "disgusting" language in text messages between them but said accusations she made that Mr Davies, now of Mayfield Road, Southampton, was a "wife-beater" were "just words because I was angry".
She said Mr Davies had not "beaten her", only "grabbed" her to prevent her from leaving.
Ms Davis added: "I have never punched him, I do not think he would let me get away with it so I never hit him in the face, I think I have slapped him and a few things."
She also told the court she had smoked cannabis and used cocaine after Stanley's birth, because Mr Davies had offered it to her, though not during pregnancy.
Giving evidence earlier in the trial, Mr Davies said he did not cause any of the injuries or allow Stanley's death.
The trial continues.