Nikki McKibbin on Celebrity Rehab with Dr. Drew

Nikki McKibbin may have appeared to have enjoyed her time on the first season of American Idol.

But on the second season of Celebrity Rehab with Dr. Drew, the former finalist says Simon Cowell's insults contributed to her substance abuse problem.

“I came out of Idol with a lack of self-confidence. I think I had my first solo in school when I was 5, and I got more as I got older: That’s the biggest compliment in choir. I had never been told I wasn’t good enough," McKibbin said.

"Having to hear it for so many weeks from Simon Cowell killed me inside. I couldn’t get the s*** he had said to me out of my head. It drove me deeper into my depression. I wouldn’t say that this was Simon’s fault. It just added to the addict that I already was.

Here's a look at how that magnanimous shrink, Dr. Drew, dealt with the issue: