The 59-year-old former clinical psychologist, who cannot be legally named, has denied that he sexually assaulted the 15-year-old boy in his office on the NSW north coast.
The alleged victim went for two counselling sessions for anxiety in mid-2017, jurors at a District Court criminal trial in Sydney heard on Wednesday.
The boy told the jury that he felt the first of these sessions was "a bit off".
The psychologist allegedly referred to watching pornography on his phone and suggested the teen go to a nearby nudist beach.
"(He stated) I should go some time to relieve stress and to relieve anger," the complainant told the court.
At a second session a week or two later, the alleged sexual assault occurred.
The psychologist is accused of sitting next to his patient and forcing the boy to masturbate him. He then allegedly raped the boy.
"All of a sudden where was just intense pain and I couldn't stop crying - I'd never felt pain like that before," he said under questioning by crown prosecutor Steve Wilkinson.
"I was embarrassed with what was happening - pain, scared, terrified for my life."
After the alleged sexual assault stopped, the psychologist told him to clean up, handing him a box of tissues.
As he was about to leave to go to his mother waiting in the car outside, the alleged victim claims he was threatened.
"He said 'just remember if you tell anyone, I'll kill you'."
The complainant said he had to lean in the side while sitting afterwards in his mother's car because of the pain, which he described similar to having "broken a leg or broken a bone".
He told his mother at home he did not want to return for another counselling session, the jury heard.
The psychologist has pleaded not guilty to one count of indecent assault and one count of aggravated sexual intercourse without consent - both charges relating to an alleged victim under 16 years old.
Earlier on Wednesday, defence barrister Anita Betts said her client denied any sexual misconduct, including the claimed references to pornography or nudist beaches.
"(His) case is that he appropriately offered counselling to the complainant and conducted as a counsellor ought," she said.
"He strenuously denies the allegations."
The trial continues on Thursday.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
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