Michelle will be lending her talents as a freshmen stylista to Coach’s “Poppy” line for young adults.

The collection debuts next spring.

According to a scoop from CelebrityRoyale.com, the drama started when Pete and Ashlee ran into Michelle Trachtenberg at the DJ Hero party at LA’s Wiltern Theater on Monday night. Michelle and her new man sat directly in front of Pete and wife Ashlee. The two couples pleasantly chatted and things were fine — and then there was a turn.

“Pete and Ashlee had a pleasant conversation with Michelle and her boyfriend for close to 20 minutes,” says a champagne-poppin’ spywitness. ”Ashlee got very very drunk and she also kept making frequent bathroom trips.”

“As the evening went on and Ashlee started to get sloppier, things got out of control,” a partygoer confesses. “A loud and obnoxious Ashlee began giving her husband a lap dance. She was staring directly at Michelle and starting hurling insults at her..She was grinding up on Pete like a stripper. It was actually pretty disgusting!”

A completely wasted Ashlee screamed at Michelle, “I hope you know, the whole time you were dating Pete, I was fucking him!”

Celebrity Royale writes: “Michelle Trachtenberg was clearly not as drunk and decided to remain classy. She said, ‘I’ve never said bad things about you. I’m happy for you guys.’ Ashlee continued to get loud and got in Michelle’s face. Finally, Mark Hoppus’s wife had to drag Ashlee away from Michelle to avoid a physical assault….”

A rep for Ashlee admits that the Melrose Place star lashed out at Michelle in her drunken stupor, but adds that she has apologized: “It was just a misunderstanding,” Ashlee’s rep claims. “Ashlee has since apologized to Michelle and they remain on good terms.”

Michelle Trachtenberg has inked a multi-episode deal to reprise her guest role as “Georgina Sparks,” arch nemesis to Blake Lively’s “Serena,” on the smash CW series Gossip Girl.

According to EW.com’s Michael Ausiello, Michelle will return to G.G. toward the end of the season.

Michelle Trachtenberg is just as unpleasant off-camera as she is on The CW’s smash small screen soap opera Gossip Girl, a friend of the actress told the New York Post.

A friend of the starlet told Page Six that when she talks about the show, “Michelle deliberately leaves out any girl cast members,” like Blake Lively or Leighton Meester. Adds the source, “If you ask her about them, she just goes silent and changes the topic.”

Harriet The Spy Meets Gossip Girl: Actress Michelle Trachtenberg will be joining The CW hit Gossip Girl for several episodes.

Michelle is set to play Georgina Sparks, a “fresh out of rehab” rival created to torment star Blake Lively’s character, Serena Van Der Woodsen.

Gossip Girl airs at 8 p.m. EST / 7 p.m. CST on Monday nights.