He is in jail today after entering guilty pleas to seven serious child sex offences against an altar server and a teenage boy and girl.

Perrin first sexually abused the teenage altar boy during an altar servers' picnic in the Newcastle area, after walking the teen to a children's play area.

"I experienced things that day that no child should experience with an adult, and he began a path that would lead to further abuse," the former altar server told Newcastle District Court Judge Tim Gartelman today during a sentencing hearing.

Perrin groomed the teenager by "driving me around, providing a freedom I hadn't known until that point".

"We'd drive in his car smoking and listening to the radio, going to places around Newcastle and Lake Macquarie that I'd never visited," the former altar server told the court in a victim impact statement before Perrin was sentenced to five years' jail, with a minimum sentence of two and a half years.

Perrin gave the teen alcohol and cigarettes and repeatedly sexually assaulted him at Perrin's home.

The court was told other teenagers stayed at the home where Perrin offered freedom.

"At that young age we desire the adult pleasures we cannot - and should not - have access to: freedom of access to alcohol and cigarettes, freedom of sexual exploration, and freedom from the seemingly-oppressive state of school," the former altar server said.

"Matthew provided all of these, but we didn't know the true long-term cost. The initial price I paid as a child seemed reasonable, but the truth is as I have grown the impact has outpaced it."

Perrin entered guilty pleas to seven offences including five charges of sexual intercourse with a child under 16, aggravated indecent assault and commit act of indecency.

The former altar server told the court he was left dealing with serious long-term impacts from the abuse, including lacking trust in people and relationships and feeling anger and an inability to forgive Perrin.

"I have frequent recollections of what happened," the former altar server said.

"So much happened over an extended period. There are so many day-to-day triggers that make me remember what happened, and respond with either anger, guilt, sadness or some combination of the three. Few days - and fewer nights - go by where I am not left dwelling on the effect Matthew's actions have had.

"I often take sedatives in order to try to regulate the background noise of my mind, much of which is to do with Matthew, and the continuing effects of his abuse."

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