I just turned 40, and my youngest sister is nine years younger than me. My mom nursed her pretty much anywhere, and no one was the wiser. Sis would actually pull a little blanket up over her head and go to town. I don’t remember anyone freaking out or even commenting about it, and I was at an age where that kind of thing would have been excruciatingly embarrassing. I would remember. I never really thought anything about it until I started running onto more and more women like your guest, women who intentionally go out of their way to prove, “I can feed My Baby here and if you don’t like it you are a Horrible Unenlightened Prude!” and heard too many stories of people laughing- laughing! - when they accidentally squirted a total stranger. That’s disgusting! Now I am one of those women who don’t want to see it anywhere, anytime. I probably would have tra-la-la’d along through life without caring one way or another until the milk brigade insisted on shoving it in my face as some kind of political act at every Starbucks and Panera Bread just looking to pick a fight. So … screw it … I’ll pick up the rope.
I would have either A) Whipped mine out at the table, too, with a “Hey, I didn’t know it was going to be that kind of party! Let me get the glitter!” or B) Asked her to leave. I think so, anyway. I've been thinking abou it and it just sounds like such an uncomfortable situation all around I may have just sat there and downed wine waiting for it all to go away.
I don't envy you OP.