Explain to your gf that you were talking about her and then he made some not-so-nice comments, and in the heat of the moment you told him her salary. That's what happened, right?

I know some people that only ever talk about money, real estate, and their weeks-long vacations, and upcoming weeks-long vacations, and spams pictures of hotel rooms and BnBs that they stay at through email. (No, they don't use social media to do that stuff even though that's what it's made for.) I dislike them but every now and then I meet them only due to obligation. I refuse to participate their game. So far I managed to keep my mouth shut.