UFC's Paige VanZant says she was sexually assaulted at 14

VanZant opens up about sexual assault in new book (2:17)

Paige VanZant joins Get Up! to share her remarkable and struggle-filled journey to the UFC. (2:17)

UFC flyweight fighter Paige VanZant, speaking to ABC News for an interview that aired on "Good Morning America" on Tuesday, says she was sexually assaulted at a party as a 14-year-old and has had suicidal thoughts since.

The 24-year-old VanZant, promoting her new memoir, "RISE: Surviving the Fight of My Life," told ABC News that she had a tough childhood and was constantly bullied in high school to the point where she ate lunch alone in the bathroom.

"I didn't have anywhere to run to. I didn't have anybody to turn to," said VanZant, who grew up in Dayton, Oregon. "[It was] bad enough that I had to run into the bathroom, and I'd eat my lunch on the toilet ... because I just felt too scared to eat lunch in the cafeteria."

VanZant told ABC News that she only recently spoke to her parents about being sexually assaulted as a high school freshman.

"I felt like I was a smart girl," she said. "My parents raised me well. They raised me to know better and to have some intuition. It all went out the window just because I was so lonely.

"I was in so much pain, I just ... all I could think about was, 'Wow, I have somebody who wants to be my friend,'" she said of the alleged assault. "When I walked in the door of their house, I was like, 'This probably isn't such a good idea.'"

VanZant said that night, and the continual bullying that followed, led her to contemplate ending her own life.

"I didn't see any other way out," VanZant said. "When you're in that position, when you're feeling that much pain, it's not that you want to die. You just don't want to be in pain anymore."

VanZant is 7-4 as a professional mixed martial artist. She joined the UFC in 2014 and won her first three fights but has struggled since, dropping three of her past four matchups. She is coming off a unanimous decision loss to Jessica-Rose Clark in January.

The former "Dancing With the Stars" contestant said that competing in MMA "saved my life."

VanZant told ABC News that she hopes her book inspires others who have gone through similar difficult experiences.

"I really hope that if I can change one life, then me telling my story is worth it."