The 42-year-old reality star admitted as much in an interview with William Shatner on Brown Bag Wine Tasting this week. She and the 41-year-old actor divorced in 2010 following Cibrian's affairs with LeAnn Rimes and other women.
"He had extra girlfriends, I guess you can say," she told Shatner. "He had some ladies on the side. I tried [to forgive him] but when I found out there was more than a couple, I decided I was better off on my own."
"It made me a better person to go through that and to figure out that it had nothing to do with me," she said. "It's almost like a death. You mourn, you die a little bit. Who you were as a wife and a mother dies and you're no longer that person."
Glanville and Cibrian married in May 2001, and are parents to two sons: 12-year-old Mason and 8-year-old Jake. The actor, who also cheated with Scheana Marie Jancan, wed Rimes in Apr. 2011. The singer was married to Dean Sheremet at the time of her affair with Cibrian.
Glanville is known for starring on Bravo series The Real Housewives of Beverly Hills, which she joined as a series regular in season 3. The reality star often updates fans with photos of her sons on Twitter, including a beach day the boys took this week.