Matthew Perry's assistant details betrayal

New court documents have revealed the depth of betrayal felt by Matthew Perry's family toward his live-in assistant, Kenneth Iwamasa.

Iwamasa, who was paid $150,000 annually, has pleaded guilty to conspiracy to distribute ketamine and admitted to administering the fatal injections that led to the actor's death.

The family's letters describe Iwamasa as a 'trusted companion' who instead became a 'deadly enabler' and de facto doctor.

The assistant is now cooperating with prosecutors in the cases against four other co-defendants, including a licensed physician and a notorious drug distributor.