Gail O'Rorke, 43, of Kilclare Gardens, has denied assisting the suicide of Bernadette Forde on 6 June 2011.
Ms Forde died at her home in Dublin on 6 June 2011 after being denied travel to a clinic in Switzerland.
Ms O'Rorke told police it was agreed that another friend of the deceased, Mary Lundy, would be present.
The deceased was diagnosed in 2001 with progressive multiple sclerosis and her condition was compounded by a car accident in 2008 that left her using a wheelchair.
In the police interviews, Ms O Rorke said Ms Forde had arranged for her to stay in a hotel in County Kilkenny so she would be out of the way and not be implicated in the suicide.
She said after Ms Forde's death, Ms Lundy had told her what had happened at Ms Forde's home on the evening of 5 June 2011 when she took a lethal dose of medication bought on the internet.
She said Ms Lundy had sobbed and told her it was the hardest thing she had ever done. She told her she had left the house when Ms Forde was close to death.
Ms O'Rorke told police that she and other family members and friends knew about Ms Forde's plan.
Ms Forde had received a number of visitors on the morning of 5 June and it was known that she planned to take a lethal dose of medication later that day, she said.
In her interviews after Ms Forde's death Ms O'Rorke said she, Ms Forde and Ms Lundy had "sobbed" after she broke the news to Ms Forde that police had intervened to prevent her travelling to Zurich to avail of the services of the organisation Dignitas.
Ms O'Rorke told police that she was personally relieved, but that relief later turned to guilt because her friend's life was falling apart.
After this, she said Ms Lundy researched other options for Ms Forde.
"I took a step back and Mary took a step forward."
She said she did make a money transfer to Mexico but was unaware what it was for the medication that Ms Forde later used to take her life with. She said she only later found out what the package contained.
The prosecution evidence in the case has now ended.
The case is expected to last for another week.
A Dublin woman on trial for assisting a suicide told police she was not present when her friend took a lethal dose of medication, but another friend was.