The fashion boutique owner was responding to magazine comments by Goodger which claimed that Mecklenburgh was never in a proper relationship with Goodger's former fiancé Mark Wright.
Goodger had previously written in her New column: "The truth is, Mark wasn't dating Lucy - he was going out with her on a TV show. They would arrive for filming separately and me and Mark would go home together.
"He would tell me it was only for a storyline, because if he had been in a relationship with her, I would not have had anything to do with him."
Mecklenburgh reacted angrily to the allegations, tweeting: "I never comment on this girl but she is seriously stupid! (sic).
"I was asked constantly to come on Towie as the guy I was seeing had started filming it.. I loved my job so said NO! But they insisted & I gave in.
"I'm not an actress! I came on a tv show because I was asked as the guy I was dated was in it."
She continued: "Lauren made my life hell the whole time & has just admitted that from day 1 of me dating him she shagged him every night still!?!
"Because he was only pretend dating me in front of a million viewers .. Of coarse that's soooo realistic! We turned up to filming separate as I had a REAL job in london to get back from .. something Lauren has prob never done.
"Anyway I'm just sick of her lies don't care if there about herself but I don't want to be perceived as a fake x."
Her rant concluded with: "I couldn't b happier with mario & my life now .. & so glad that's all in my past!!! Now off to have my personal training xxx."
Mecklenburgh briefly dated Mark Wright after his split with Goodger during the first series of TOWIE.
However, Goodger later claimed that she was still sleeping with Wright, who soon dumped Mecklenburgh and proposed to Goodger. They later broke up for good.
Lucy Mecklenburgh is currently dating her TOWIE co-star Mario Falcone, while Mark Wright is with Coronation Street star Michelle Keegan.
Lauren Goodger is in a relationship with Jake McLean, who was jailed for over three years in 2008 for aggravated burglary.