NEW YORK -- Olympic gymnast Simone Biles has come forward to accuse former Dr. Larry Nassar of molesting her while he worked as a physician for USA Gymnastics. Biles, who won four gold medals at the 2016 Olympic games, wrote on Twitter Monday afternoon that she was among those who were victims of Nasser's abuse.

"I too am one of the many survivors that was sexually abused by Larry Nassar," Biles wrote. "Please believe me when I say it was a lot harder to first speak those words out loud than it is now to put them on paper."

Nassar pleaded guilty to seven counts of criminal sexual conduct in November and faces decades behind bars. More than 125 women and girls have filed lawsuits against Nasser claiming he molested them during treatment sessions.

In her statement Monday, Biles said she was "reluctant to share" her story for several reasons but had come to realize the abuse was not her fault.

U.S. gymnast Simone Biles seen at the Rio 2016 Olympic Games in Rio de Janeiro on Aug. 11, 2016. Getty

"After hearing the brave stories of my friends and other survivors, I know that this horrific experience does not define me," she continued. "I am much more than this. I have promised myself that my story will be much greater than this and I promise all of you that I will never give up. I will compete with all of my heart and soul every time I step into the gym."

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In reaction, USA Gymnastics released a statement Monday evening to CBS News saying in part it's "heartbroken, sorry and angry" and that their support for Biles and all athletes who come forward "is unwavering."

"USA Gymnastics is absolutely heartbroken, sorry and angry that Simone Biles or any of our athletes have been harmed by the horrific acts of Larry Nassar," the statement read. "USA Gymnastics' support is unwavering for Simone and all athletes who courageously came forward to share their experiences. We are our athletes' advocates. USA Gymnastics will continue to listen to our athletes and our members in our efforts of creating a culture of empowerment with a relentless focus on athlete safety every single day."

Nassar, 54, worked as a team doctor at Michigan State University and USA Gymnastics, the Indianapolis-based group that trains Olympians.

Olympians Aly Raisman, McKayla Maroney and Gabby Douglas have also said they were molested by Nassar accompanied them at workouts or international events.