Elizabeth Vargas' enraged ex told her she'd be the first, among many, to die as heavily-armed police waited outside and readied the SWAT team for her recovery.

TMZ got this video from inside the former-'RHOC' star's home Tuesday as her ex, Ryan Geraghty, barks at her ... "I'm taking you out, and then everybody else. They can shoot me if they want. I don't give a f**k anymore, I've got nothing to lose."

It's an especially chilling statement because, we're told, armored vehicles and SWAT officers had gathered outside Liz's home Newport Beach home at this point.

Clearly irked that Elizabeth had gotten the police involved, Geraghty says, "Bring the big boys, how f**king dare you."

TMZ broke the story, cops got Vargas out safely, and Geraghty was eventually arrested after an hours-long standoff. Vargas had originally called the cops to report Geraghty for extortion, but things took a turn for the worse when he showed up armed, and made his way inside her house.

We've also obtained footage from after the arrest, showing a police drone making its way through the home to make sure things were clear before SWAT does a final check.

Elizabeth was outside NOBU in Malibu just 24 hours after the ordeal, and told a photog she was happy to be alive ... and was considering buying a gun.