These days, Leah Messer is a Teen Mom success story on par with fellow fan favorite Chelsea Houska.

But if you're a longtime viewer of the show, then you know that Leah had to go through hell in order to get where she is today.

In some of TM2's most harrowing episodes, Leah grappled with a severe addiction to prescription painkillers.

And there was a time when it looked as though it was battle that Leah might not win.

That ugly chapter in Messer's life was reopened this week when the mother of three was subpoenaed to testify in the trial of her former doctor, Sriramloo Kesari.

According to prosecutors, the disgraced physician was “involved in over prescribing medication" and Leah was one of the patients who became addicted as a result of his recklessness.

The DA's office charged Kesari with “routinely prescribing various Schedule III controlled substances, including Buprenorphine Hcl and Suboxone for his patients outside the usual course of professional practice and without legitimate medical purpose.”

“Defendant Sriramloo Kesari did knowingly, intentionally, and without authority, distribute a mixture and substance containing a detectable amount of Buprenorphine Hcl and Suboxone without a legitimate medical purpose and outside the usual course of professional practice from 2018 to 2019," reads one filing.

A press release from the Department of Justice further explains:

"Kesari, who was at times physically located in California, operated a cash-only operation whereby he would sign prescriptions that his employee would distribute in exchange for cash payments. "

While the content of Leah's testimony has not been made public, Messer's recent memoir provided a harrowing glimpse at her battle with addiction.

“At first, the medications helped dull the pain in my body and my mind, but at some point, they stopped helping," Leah wrote.

"Now, I’m starting to think they might be part of the problem," she added.

“I just want to feel normal, but I’m either in so much physical pain that I can barely stand, or so foggy from the pills that I look like a junkie.”

At her lowest point, Leah fell asleep while holding a child, an incident that was captured by MTV camera crews.

After years of denying that she struggled with substance abuse, Messer now admits that she resorted to using street drugs like heroin at her lowest point.

Finally realizing the urgency of getting clean, Leah weaned off the drugs with the help of her mother, a registered nurse, and she says that she hasn't used yet.

Obviously, Leah's battle was courageous before the events of this week, but now she's taken another admirable step by fighting to ensure that no other patients will suffer as a result of the "care" they receive from Kesari.

In all likelihood, this is not the sort of victory that Leah will boast about on social media, as doing so might prompt an uncomfortable discussion about a very dark time in her life.

But the important thing is that she and her loved ones will know what a tremendous difference she's made.