Tl;DR How do you handle the shit test, "I saw your girlfriend, oh wow, she is beautiful!!"

Out last night to a bar with a group of friends, 4 guys and 2 girls. I've barely had anything to drink, start enjoying myself by dancing and dgaf.

One girl (hb7) in my group is getting really close, trying to dance with me, touching me, and keeps putting herself near me. IOI's couldn't be more clear. But I have a girlfriend, and she knows that, so I eject from the group and start talking with other girls around me at the bar before she can get too close. Even though I am in a relationship, I enjoy approaching and practicing my opening skills.

I flirt with other girls pretty successfully in front of hb7 for a while, then return to the group as if nothing happened. I get back and she can't stop shit testing. I don't really care, I can handle my own for most of them.

But then she gets really passive aggressive in her tone and asks "I saw your girlfriend on instagram, oh she's so beautiful!!". It was a sarcastic and passive agressive tone so I tried to agree and amplify. I said something along the lines of "yeah she's the prettiest princess in all the land" in the same tone with a smirk on my face. But the she kept reiterating how beautiful she was and wouldn't stop until I literally walked away. Like, I get it chick, my gf is hot lol.

How could I have handle that shit test better? Why would she keep reiterating? Any general advice?