Matthew Perry’s mother, Suzanne Perry, has slammed her late son's assistant, Kenneth Iwamasa.

She read out an emotional victim impact statement ahead of Iwamasa's sentencing for helping supply the ketamine that ultimately killed the TV star in October 2023.

"He insisted on speaking at Matthew's funeral," the letter, included in court docs obtained by Page Six, read.

"He clung to me and the family as if he was somehow the good guy who tried to save Matthew."

Suzanne added that after Iwamasa "killed" her son, he kept a close eye on her.

"He sent me songs, he drew a little map to help me find my way around the cemetery. If he saw a rainbow - one of Matthew's favourite things - he would call me," she penned.

Suzanne told the court that she and her family had "trusted a man without a conscience", and Matthew had paid the price.

"He had known Kenny, and so had we, for 25 years," she detailed, adding, "Mathew trusted Kenny. We trusted Kenny. Kenny's most important job, by far, was to be my son's companion and guardian in his fight against addiction."

"Kenny knew, should he feel unduly pressured, that with one phone call to any number of the people in Matthew's orbit, reinforcements would be on the way, and his job would be safe," Suzanne revealed.

But instead of protecting Matthew, "he aided and abetted" his addiction.

The heartbroken mother shared of her son, "He was, in spite of all we went through, my heart and soul. Nothing takes this pain away, nor will it, I am sure, for as long as I live."

The Friends star's former live-in assistant is scheduled to be sentenced in federal court on May 27.

He faces a statutory maximum sentence of 15 years in federal prison after pleading guilty to one count of conspiracy to distribute ketamine causing death.

Matthew Perry, who openly struggled with drug addiction for decades, was found dead in his jacuzzi on October 28, 2023, at the age of 54.