updated 05/04/2010 AT 8:00 AM ET
•originally published 05/03/2010 AT 6:00 PM ET
Bones star David Boreanaz is opening up about reports that he has been unfaithful to his wife of nearly nine years, Jaime Bergman.
“Our marriage has been tainted with my infidelities,” the actor admits to PEOPLE. “I just want to be open and honest. I was irresponsible.”
The actor, 40, is coming forward, he says, because a former mistress, whom he declines to name, contacted an attorney and threatened to contact media outlets.