The 25-year-old singer's relationship with the Good Charlotte guitarist ended in 2012 after around a year together and two of the songs, 'No Man Can' and 'I'm in Love With You (In Your Hands)', on her upcoming LP allude to the break-up.
She said: ''It's a journey from before I was with someone to when I was with them and then afterwards. The songs that came from the break-up definitely fuelled things in me. I was writing constantly, just getting it out of my system.''
Although her failed romance with Benji - who previously dated Paris Hilton, Sophie Monk and Holly Madison - has inspired some of her latest music, she insists her next record is not a break-up album like Adele's '2'1 or Amy Winehouse's 'Back to Black'.
Eliza - who is due to release the album in October - explained: ''It's not a break-up album, though. Maybe the break-up triggered it but it's really about discovering things about myself I didn't know before.''
Many ticket-holders couldn't get into the O2 Arena show on Tuesday night (September 19th) because they didn't bring photo ID to match their booking.
An album re-release, a new song and a documentary mark the singer's legacy this year.
The actor plays the titular hero in the forthcoming adaptation.