Joanna Krupa's lady parts have finally had enough of Brandi Glanville alleging there is a major funk down there ... so Joanna's gearing up to take Brandi to court.
According to a legal letter sent from Krupa's lawyer to Glanville -- and obtained by TMZ -- JK is warning the 'RHBH' star ... her ass is about to get hit with a defamation lawsuit.
Brandi and Joanna have been feuding since November 2013 when Glanville went on "Watch What Happens Live" and claimed she'd heard from a friend ... Krupa's nether region "smelled."
She re-iterated that again just last month ... which made Krupa go ballistic about Glanville to a TMZ photog -- and most likely led to lawyers drafting this letter.
The suit has not been filed yet, but Krupa and her attorneys say ... it's coming.