The former Real Housewives of Beverly Hills star, 51, says she had been nearly 3-and-a-half years sober ahead of her arrest. A few weeks before, she'd had a glass of wine with a friend, and the night of her arrest, she drank at her daughter Brooke's home.
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"I had a drink at her house. I felt horribly guilty. I thought, 'I need to go home. I can't be at my daughter's house like this. This is terrible,' " she says in a clip for Tuesday's Watch What Happens Live.
After leaving her daughter's house, Richards ended up pulling into the nearby Beverly Hills Hotel to avoid drinking and driving. It was one of her usual hangouts, but one she hadn't frequented recently.
"When I walked in, nobody knew me there," she says. Richards tried to sit in her favorite booth after being informed the hotel was closing soon.
"He said, 'If you don't leave, we're calling the police, and I really thought he was joking. And he called the police. And one thing led to another," says Richards. She later received probation in a plea deal and was ordered to attend Alcoholics Anonymous.
Richards also opens up about RHOBH's Lisa Rinna, with whom she has had a tumultuous relationship.
"Every time I've tried to talk to her, it's dangerous. She confronts me in a not-so-nice way. I did try to speak with her and ask her why she kind of has it out for me," Richards says of Rinna, 52. "I don't get it. It's been a whole almost two years since I've seen her, and I'm a 'vicious, vile dog' and I'm 'crazy.' It's just concerning to me."
Watch What Happens Live's one-on-one with Richards airs Tuesday at 8:30 p.m. ET.