Arnold Schwarzenegger: I'm Spilling My Guts ... In a Book!

Arnold Schwarzenegger is breaking his silence -- with an autobiography.

According to his rep, Arnold has been working on the book for over a year -- long before news broke of the actor's infamous affair with his housekeeper.

The book -- tentatively titled "Total Recall: My Unbelievably True Life Story" -- will address the affair and his crumbling relationship with Maria Shriver ... but a source tells People.com, it won't be a tell-all.

Arnold plans to put pen to paper soon -- while he shoots his new movie "The Expendables 2."