Finch, 41, is facing a sentencing hearing in a Sydney court after pleading guilty in August to one charge of using a carriage service to transmit, publish or promote child abuse.
The former NRL star was arrested in December 2021 as one of eight men accused of being involved in a telephone chat line where police alleged sexual abuse of children was discussed and abuse material was swapped.
Six other charges against Finch were withdrawn in August.
Finch told the court on Monday he left "twisted" messages on FastMeet - a service for gay men - as he thought "hypersexualised" users could be a last resort to get drugs.
Finch said his only goal in leaving the messages was to obtain cocaine, telling the court that he was introduced to the service by drug dealer connections.
He said in the COVID-19 pandemic dealers were not on the roads and that he tried every dealer in his phone before turning to FastMeet in desperation.
Finch viewed transmitting the messages as a "lead in" to his ultimate goal of getting drugs, the court was told
"Have you ever had a sexual interest in children?" defence barrister Mike Smith asked Finch.
"Never," Finch replied.
Finch stopped using the line in early 2021 after he got a reply from a user "who wanted to take me up" and mentioned "granddaughters", the court heard.
The reply made him realise his behaviour could contribute to pedophilia.
"It made me utterly sick, I was disgusted," Finch told the court.
"I instantly told him he was a sick f*** and to f*** off.
"I just wanted to strangle the bloke through the phone."
Finch said he was ashamed and disgusted to have left the messages in the hope of scoring cocaine at the end of drug-fuelled benders.
"That period I really spiralled out of control with my drug use," he said.
He had now "lost everything", was on Centrelink benefits and was unable to find work despite applying for 300 jobs.
"I understand why no one wants to come near me," he said.
"I've got no one else to blame but myself ... it's hurt so many other people and that's what I'm sorry for."
Asked whether he accepted his behaviour was a "inexact" way to obtain drugs, Finch said: "It was a terrible method and one I'm deeply ashamed of".
Psychologist Chris Lennings, in his evidence, told the court Finch's offending was not sexually motivated, but that it was key the ex-footballer was subjected to "biological drug testing", such as hair follicle tests, in the future.
"In my assessment he does not present as having a sexual deviance ," Dr Lennings said via audio-visual link.
Late on Monday, two family friends of Finch gave evidence, describing him as a loyal, kind and caring man whose offending conduct was out of character.
Finch played three State of Origins for NSW and won a premiership with Melbourne Storm in 2009.
His crowning moment came in the 2006 Origin opener when he kicked a match-winning field goal for the Blues.
In his post-football life, Finch has suffered mental health issues and has spoken publicly about his battles with substance abuse.
The hearing in Downing Centre District Court continues on Tuesday.
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