"I cut my wrists with a steak knife," Brendon said.
The actor, who's been arrested four times in 2015 and entered rehab in June, walked off the show in August but returned to finish his talk with Dr. Phil on Tuesday.
Brendon said he'd blacked out during most of the incidents that led to his arrest, including the alleged domestic altercation with his girlfriend in October. He also talked about being molested when he was about 10 years old.
"I think about it every day of my life," he said. "When you're molested for a couple years and you're blamed for it by the people who are supposed to be your protectors, there's going to be a lot of confusion and a lot of sadness."
Brendon checked into a treatment center at the end of the interview. Watch the heart-wrenching footage from the show below.