'Real Housewives of OC' Star Gretchen Rossi -- Alleged Ex Wanted Re-Trial... Judge Says HELL NO

"Real Housewives of Orange County" star Gretchen Rossi can breathe a sigh of relief ... the man who lost a $500,000 lawsuit against her asked for a retrial claiming the verdict was decided by a bunch of starstruck jurors -- but a judge just shut him down.

TMZ broke the story ... Gretchen sued a man named Jay Photoglou back in 2010 for defamation and a slew of of other things, claiming Jay lied about being her ex, trashed her in the media and as a result, she lost job opportunities.

The case dragged on until last November, when a jury sided with Gretchen and awarded her $523,250 in damages.

But Jay recently filed docs in CA court demanding a re-trial ... claiming the jury's verdict was based solely on popularity and NOT the evidence because Gretchen is "a beautiful actress and [Jay] is a used car salesman."

Gretchen fired back with docs of her own -- arguing she won the $500k fair and square.

On Feb. 8th the judge agreed with Gretchen and said there was "sufficient evidence to support the jury's finding." And adds, "A verdict of $500,000 is not excessive."