I didn't need a breathalyzer to know my boyfriend was lying. He was an alcoholic. He drank. Every day. And he lied about it every time I asked him if he'd been drinking.
From what you've shared here, your wife lies about her drinking, she lies about where she's been, who she's been talking to, who's she's been sleeping with, who was responsible for her multiple car accidents. She lies.
She's a drinker, a cheater, and a liar. That's a given. So why waste your time, money, or energy on a breathalyzer? Wouldn't it be a better use of time to focus on how to protect your children from her?