A mother accused of murdering her two-year-old son has told a court her decision not to seek medical help for the toddler is one she will regret for the rest of her life.

Rachel Trelfa, admitted it was "a possibility" Liam Fee might die and that if she had taken him to hospital for treatment for a broken leg, he would be "alive" today.

Trelfa, 31, admitted her conduct had a part to play in his death as she "should have got him help".

The High Court in Livingston heard that despite suspecting he had had a broken leg for several days, she went to look after her horse for three hours on March 22, 2014, the day Liam died.

Trelfa said she now regretted not seeking medical help for her son.

Fee is on trial at the High Court in Livingston alongside her civil partner Nyomi Fee, 28, where they deny murdering the toddler at a house near Glenrothes in Fife by repeatedly inflicting "blunt force trauma" to his head and body.

Questioned by prosecutor Alex Prentice QC, she said: "I know I should have got Liam help. It's a decision I'll regret for the rest of my life."

Fee said she took responsibility for the decision not to get help as she was concerned the child would be taken into care, and she agreed under questioning that she had threatened to leave Nyomi Fee if she made the call.

She said: "I wasn't thinking straight at all. I should have got help, I failed to do so. It was the wrong decision to make. I was frightened that they wouldn't believe me."

Trelfa said: "I completely failed Liam."

Questioned by her lawyer Brian McConnachie QC, Trelfa initially denied Liam's death was anything to do with her.

Mr McConnachie asked her for a second time: "Do you think his death has anything to do with your conduct?"

She replied: "I should have got him help, so yes."

She denied physically causing Liam injury.

He asked her: "Did you come back from your three hours at the stables and assault him by striking him so hard you ruptured his heart?"

She replied, "No, I did not." She also denied allegations of abusing two other boys, one of whom the couple are accused of falsely blaming for Liam's death, including accusations of keeping him in a cage and cutting him with scissors.

Mr McConnachie asked her: "Why are they saying you did?" She replied: "I don't know."

Trelfa became emotional on occasions when telling the court about the night Liam died.

She said her partner screamed for her to come to his bedroom where she was trying to get him out of his buggy, and saw he was "all white".

She said: "I fell to the floor. I thought he wasn't breathing."

Trelfa said when she saw the boy she is accused of falsely blaming for Liam's death he put his head down and she "knew he had done something".

She added: "I was completely distraught and devastated. I didn't know what was happening. I didn't know what to do. I had so many different emotions."

Trelfa said she asked the boy what he had done and he said "I did this", putting his hands to his mouth and throat.

She told the court: "I said 'You've strangled him or suffocated him haven't you?' and he said 'Yes'."

She denied there was any delay between Liam being found and the ambulance being called, and said she was "absolutely devastated" when paramedics told her he was dead.

She claimed the boy she is accused of falsely blaming for his death had shown "sexualised behaviour" for years and in the months before Liam died had began assaulting him sexually and physically, as well as another boy.

The court was shown a picture of the toddler's leg snapped in two and Trelfa said after discovering it she did not take him to hospital, and admitted searching on Google questions including "How long can you live with a broken bone?" and if wives could live together in prison.

Mr McConnachie asked Trelfa: "How can it be that a mother of a two-and-half-year-old toddler who she thinks has a broken leg does nothing?"

She replied: "Because I was still scared for getting into trouble and getting him taken off me."

She added: "At the time I wasn't thinking rationally. I know it was the wrong thing to do. I should [have got treatment], I completely should [have]. I was just so scared."

In a statement she gave to police four days after Liam's death, read to the court, she said: "There are lots of other incidents involving Liam and [the boy] from the past but we would be here all day if I was to go into details.

"At a later time both myself and Nyomi would like to tell you about previous injuries caused to Liam by [the boy]."

Mr Prentice asked the witness: "Do you not owe it to the memory of Liam and his dad, who is sitting in court, to tell the truth about Liam?"

She said: "Definitely. I am telling the truth."

The case was adjourned until Tuesday when the Crown and defence will begin summing up before the jury are given directions by judge Lord Burns.