Boreanaz is best known for his roles on TV's "Buffy the Vampire Slayer," "Angel" and "Bones." He has been married to model Jaime Bergman for nearly nine years and they have two children.
"Our marriage has been tainted with my infidelities," the actor admitted to People. "I just want to be open and honest. I was irresponsible."
As for why he opted to go public with his indiscretions, Boreanaz told the magazine: "I was associated with a woman who I was involved with and had a relationship with ... She asked for money. I felt as though I was being blackmailed or there was some sort of extortion."
The actor went on to say he and Bergman are not giving up on their marriage.
"We're working on repairing what has been damaged so badly," he said.