Stupid Fight Big Consequences

My wife and I have a history of getting into fights over little b.s. stuff mostly when my wife is told “thats against the rules”. Yesterday, we were getting a happy hour drink, and she wanted to move to a table. The bar tender told her we cant get happy hour at the outdoor tables. This place mind you is not a “bar and grill” it’s an upscale Italian restaurant. We sit at the table and she is hell bent on getting happy hour at the table. Till eventually I tell her she is being tacky. Then she is insisting on me explaining every bit of context. Eventually she asks the waiter, he gets nervouse because this against their rules and affects his tip at the end of the service. She notices me embarrassed and the argument continues. I repeatedly tell her I do not want to argue in a public place. She continues and then leaves. I pay the check we meet and go to the car. The argument boils over into a fight. She hits me while Im driving. It was ugly. Im pretty sure I want to separate but we have two kids and I don’t want to damage their lives. I don’t want to seperate over this fight, but these happen all the time when somebody tells her she cant have it her way. Im so tired of wasting energy on this bullshit. My thoughts are she is a narcissist. What do you all think?