The couple met in a London pub in 2003 and were married for two years before divorcing in 2009 after a series of violent rows and battles with drug addiction.
They stayed in contact right up until her death last month, and a source told Now magazine that for the right price, Blake will consider lifting the lid on their relationship.
'He's prepared to betray Amy because as far as he's concerned, he needs to get what he's owed,' said the insider.
'Blake's been planning to write a tell-all on Amy since she became famous.
'When they were together he'd film her and sell videos to the papers, but there are many hours of footage and photos he hasn't released.'