'Teen Mom' Star Amber Portwood: Why I Chose to Go to Prison

Amber Portwood, star of MTV's "Teen Mom," made the difficult decision Tuesday to quit her court-ordered rehab in favor of a five-year prison sentence, stemming from her December 2011 drug arrest.

"In my situation, I felt in the program there were a lot of eyes on me. And it was very uncomfortable. I was not using my anti-psych medication even," Portwood, 22, said in a new jailhouse interview with ABC News on Wednesday. "You know, I was very depressed, all alone, all bitter at everybody. I felt like that wasn't the life I wanted to live. I felt like I'd rather do my time and get it over with and make the best out of the situation that's been handed to me."

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"It wasn't just the program," she explained. "It was the fact of being alone. It was personal. You know being alone, feeling like you're hopeless, you have nothing, feeling like an addict and you're never going to change, even though in your mind you're working so hard, but every time you get to court it's not good enough."

Portwood also admitted she's recently tried to overdose on pills to end her life. "I took 30 Suboxone within three days," she said. "The depression took over. I'd just take four to five at a time underneath my tongue, and nod out. I had more than addiction problems. I had, you know, mental problems, too."

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And this wasn't the first time. The MTV star tried to commit suicide in June 2011, and Gary Shirley -- her on-off boyfriend and the father of their daughter Leah, 3 -- called 911.

Shirley now has custody of Leah, and Portwood said, "We'll still have a relationship. We still do."

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While Portwood is in prison, she plans to get her life back on track. "I'm not just going to sit," she said. "I'm going to substance-abuse classes. I'm going to get my GED."

"There's nothing lower than trying to kill yourself. That's why it's probably hard to understand why I did what I did," she said. "But when you mentally know that, you're not right. You're 22, and you tried to take your life twice. And you're 22, and you're still here, you don't want to mess that up."