Brandi Glanville got married over the weekend in a spur-of-the-moment Vegas ceremony and RadarOnline.com has exclusively learned her new husband's ex-wife is fuming over the stunt!

"She was my best friend until she started an affair w my ex hus Darin behind my back!!!!" Darin Harvey's ex-wife, Michelle Harvey posted on her Twitter account Tuesday afternoon.

PHOTO: Click Here To See Michelle Harvey's Twitter Rant