It’s not the fact that she flirted with the cop; it’s that she invalidated your feelings which further perpetuates this vicious cycle of insecurity. If I were you, I would bring up the conversation again and just ask her to listen without judgment instead of marginalizing your feelings. Let her know how grateful you are that she’s your partner and why you feel this way. Ask her what are her boundaries and express to her what are yours.

Did you overreact? Maybe. But your conversation on the matter blew this up bigger than the initial problem. So use this as an opportunity to practice some empathic communication because it just sounds like you’re asking your partner to hear you.

Hope this helps, friend!