A sex tape of the pair heard them discussing getting Joanne Mjadzelics pregnant so they would have a child they could sexually assault.
The couple also exchanged indecent images of children online, and talked about what they planned to do in the future.
During one internet exchange, Joanne, who is a mum-of-one, signed off: ‘Child molesters till we die.’
Mjadzelics was arrested as part of Operation Globe, a worldwide investigation into Watkins’ crimes.
She claims that her actions with Watkins were intended to trap him and bring him to justice, though the prosecution dispute this.
Ian Watkins, who was once frontman of successful rock band Lost Prophets, was sentenced to 29 years in prison for his crimes.
Mjadzelics trial is ongoing after starting on January 5 2015. She pleads not guilty to the four charges against her.