In May 2011, the former California governor was embroiled in controversy when it came out that he had fathered a child with his housemaid.
TMZ reports that in Schwarzenegger's new autobiography Total Recall, he admits that Shriver confronted him about the child in couples' therapy, a day after he left his seat as governor.
The Terminator star says he initially came up with excuses when Shriver asked him if he had slept with their maid, but eventually admitted to the infidelity.
Shriver apparently made it known to Schwarzenegger that the maid had already told her about the betrayal.
The couple are now separated after a 25-year marriage, and have no plans for reconciliation.
Watch Schwarzenegger in the trailer for The Expendables 2 below: