Tori Spelling had sex with Jason Priestley too?! It's true -- and a lie detector test doesn't lie.

After news broke earlier this week that Spelling slept with her "90210" co-star Brian Austin Green, Spelling spilled even more beans to show host Louise Roe last night during Lifetime's one-hour special, "Celebrity Lie Detector." And yes, she and Priestley shared more than the same zip code.

WATCH: Tori Spelling Says She Slept With Brian Austin Green and One More '90210' Costar! 

"It was a summer fling; it was off-set," confessed Spelling, who played virgin Donna Martin on the long-running '90s drama. "It was our version of a summer romance. The "90210" version. And that was it, and we stayed great friends."

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"Oh my god, I'm gonna get in so much trouble for this," the 42-year-old reality star continued nervously.

Did she also have sex with Ian Ziering? "No." How about Luke Perry? "From the very first episode Luke Perry was on, I had a mad crush on him," she admitted, noting they never had sex. "What everyone felt on TV, we all felt in real life."

As for Green, who played David Silver -- it was more than sex. The two, she says, were a "teenage love story," even writing their own vows for their epic 90210 wedding scene because they thought the scene, as written, lacked authenticity.

"He was a little bit of my everything," Spelling told Roe, admitting that their onscreen vows during the series finale were "like real." "We grew up together. I think I was always in love with Brian."

PHOTOS: The Cast Photos of Lifetime's Unauthorized '90210' & 'Melrose Place' Movies Are '90s Perfection 

The dish didn't stop there. Beyond her real-life "90210" sexcapades, Spelling divulged details on Shannen Doherty, and what really went down when her infamously difficult co-star was fired from the show."It was getting worse and worse," Spelling said regarding Doherty's diva behavior.

Doherty was involved in several onset spats, one with co-star Jennie Garth, according to Spelling. "I remember I could hear the door fly open and everyone screaming and crying. That's when I was told the boys just had to break up Jennie and Shannen... it was like a fist fight."

The breaking point? When Doherty bolted into hair and makeup just as the cast was ready to shoot.

WATCH: Shannen Doherty Comes Across as Catty in Unauthorized '90210' Movie 

"Shannen runs in and sits down to get hair done," she remembered, "and you could just feel everyone was turning and looking. I knew someone was gonna say something."

That someone was Ziering. Spelling recalled him scolding Doherty during a "heated fight," saying, "You are a C-*-N-T: Can't Understand Normal Thinking."

Immediately following their brawl, the cast united in an effort to get Doherty fired from 90210, according to Spelling. The actress called her dad, show creator Aaron Spelling.

"I felt like I was a part of something, a movement, that cost someone their livelihood," Spelling said, crying. "...Was she a horrible person? No. She was one of the best friends I ever had."

Did Spelling think the cast made the right decision to boot Doherty from "90210?" 

"Gosh, as my friend, I wanna say no," she said. "In the workplace, as a co-worker, yeah."

WATCH: Shannen Doherty Says Her 'Heart Breaks' for Tori Spelling

For other big reveals from Tori's "Celebrity Lie Detector," read on!

Does Tori's daughter think her boobs look like 'water balloons'?

"I've had my nose done and I've had my boobs done. … I don't wanna do more surgery. I need to get my boobs re-done just because they're recalled and expired. I woke up this morning and my 3-year-old daughter (Hattie) literally came over to me and was like, 'Mom, your boobs look like water balloons.' She's right. I need new bags."

Did Tori actually sell Jason Priestley's wedding invite at a yard sale?

"I would never do that...and if I did, it was a joke."

Did dad Aaron really only leaves Tori $800K even though he was worth $500 million?

"I don't really understand the thought process behind it. He wasn't a financial guy. I grew up never talking about money… it's just, we had money. All I can think is, he assumed we would be fine. And I proved him right; I am fine. It's still confusing."

Shannen wore the bloody dress Tori lost her virginity in?!

"So it was a little, black, flirty dress with pink roses all over it," Spelling said of the dress she wore when she lost her virginity to her first boyfriend, a "normal guy." 

"Sometimes when you lose your virginity there's a little, um, blood, so I remember the dress had a little blood stain on the back of it. I was like, 'Oh my gosh, I wanna keep this, and it's gonna be kind of like that memento,' and I remember we were having a big photoshoot – it was one of the biggest ones we've ever had; it's that infamous photo where they shot us from above. So Shannen and I were going to the photoshoot together and she's like, 'Do you mind if I borrow something?' So she pulls out the dress I lost my virginity in. I'm like, 'That's the dress!' She's like, 'It's black, it's floral, no one's ever gonna see it.' She wore the dress!"

Will there ever be a #90210Reunion??

"I would like there to be, yeah. I think there should be."

Does she forgive husband Dean McDermott for having an affair?

"Um… yes and no. I haven't forgotten it. I'll never forget. The truth is, my mind has forgiven him but obviously my heart hasn't."

Did Tori really like Lifetime's "The Unauthorized Beverly Hills, 90210" or did she lie? (She lied.)

"It didn't capture the spirit of what happened in real life."