Creed frontman Scott Stapp reveals he has bipolar disorder

Creed frontman Scott Stapp is revealing for the first time his bipolar disorder and discussing the bizarre downward spiral that consumed him for six months in an exclusive interview with People magazine and ABC News' Nightline.

Stapp, 41, made headlines this past November when he released a rambling video stating he was broke and "under some kind of pretty vicious attack."

From there, Stapp's behavior became increasingly erratic.

"I was so out of my mind, delusional, turned on everyone that I loved, made wild and crazy accusations about my wife. I thought I was being followed by the government, I mean, it was a manic paranoid, psychotic episode," Stapp told ABC News. "I was driving around with...a 12-gauge shotgun in my lap. And I thought that people were trying to kill me."

Stapp told ABC News that his years of substance abuse were an attempt to self-medicate his undiagnosed bipolar disorder. In 1998, the singer said he started to feel different, just as his music career was taking off.

"I was on top of the world," Stapp said. "I had four No. 1 singles...and then all of a sudden, a depression came over me, a debilitating, physical depression."

"And at that point in time, I went into a walk-in clinic while I was on tour, sought a doctor and got a prescription antidepressant, and that's really where this journey begins," Stapp told ABC News.

Stapp entered rehab following his strange behavior in 2014 and was officially diagnosed with bipolar disorder. The singer told ABC News he is now sober and has recently moved back to Florida, where he and his wife are trying to move forward together.

"There is hope," Stapp said. "When I'm with this woman, I feel like there's always hope, and she's teaching me what real love it and I'm just very thankful for that."

Watch ABC's Matt Gutman's interview with Scott Stapp on Nightline on Wednesday, May 13 at 12:35 a.m. ET | 11:35 p.m. CT.