Sofia Vergara's ex, Nick Loeb, spilled the beans to OC Housewife/Rumorfix celebrity correspondent Gretchen (Christine -- she's adding a middle name now) Rossi at the Rumorfix Bar at Sundance over the weekend ... and boy does he DISH!

Loeb told Rossi that Vergara never returned her engagement ring, even after she broke off the relationship and fell into the arms of Joe Mangianello!

The 39 year-old businessman said it wasn't necessarily something he tried to get back (let's face it, this guy's richer than god -- his dad founded Lehman Brothers). "She’s a woman — she loves jewelry. I’m sure she’ll accessorize with it," Loeb joked to Rossi.

In fact, Nick's not hating on Sofia or on Joe; he's glad they hooked up! "I’m actually really happy she’s found someone really special in her life. Everyone deserves happiness. She was great to me for four and a half years and I wish them the best."

Nice guy!