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Simpson says she'd go everywhere with a cup that was "always filled to the rim with alcohol."

Jessica Simpson is getting candid about her alcohol abuse, this time on camera.

After excerpts from her upcoming tell-all "Open Book" revealed she battled alcoholism and a pill problem, Simpson spoke candidly about her painful past in a new interview with "TODAY." While the full interview won't air until Wednesday, two preview clips were released Tuesday morning, in which she details her struggle.

"I had started a spiral and I couldn't catch up with myself," she explained. "I was spiraling, chasing my tail and that was with alcohol."

When asked by Hoda Kotb if she worried her drinking was "getting out of control," Simpson said it wasn't a secret. "Every day I would say it and I would say it openly to everyone. 'I know. I know, I'll stop soon. I'll cut back,'" she said. "For me to cut back, like I'm an all or nothing girl, and so I didn't know it was a problem until it was."

In book excerpts, she explained that her rock bottom came after Halloween 2017. She revealed she began drinking at 7:30am that morning, with her father smelling vodka on her breath as she attended a school assembly for her daughter, Maxwell. It only got worse later in the day, with Simpson revealing she was "ashamed to say" she has no idea who got her kids into their costumes. She then took Ambien to go to bed that night and slept in, "afraid" she had failed her children.

It's then that she finally opened up to her friends about her issues.

"I completely didn't recognize myself. I always had a glitter cup. It was always filled to the rim with alcohol," she said of the cup she brought to her daughter's school that day. "I just realized that I had to surrender. It was time. I had to give it up and I was ready. I'm not going to miss another day, I'm not gonna miss another Halloween, I'm not gonna miss another Christmas, I'm going to be present."

According to Simpson, she's been sober since 2017.

The full interview with Simpson airs Wednesday on NBC's "TODAY." See more from her memoir -- which will be released on February 4 -- below.