'Real Housewives of Orange County' Star Lynne Curtin -- Happy New Year ... I'm Getting Divorced

2013 is gonna be A LOT different than 2012 for one "Real Housewife of Orange County"... former star Lynne Curtin officially pulled the plug on her marriage of 22 years, TMZ has learned.

Lynn -- who appeared in seasons 4 & 5 of the Bravo series -- recently filed docs in OC Superior Court to divorce her husband Frank Curtin, citing "irreconcilable differences."

According to docs, the couple married in April 1990 and separated in January 2012. The duo has two children together ... neither are minors.

Lynne is asking for spousal support, but makes it clear in docs that she has no clue how much property she and her husband actually have.