Nursing and Self conscious

So I don’t have a super great relationship with my in-laws, but I try. They’re not the best of people, as you’ll hopefully see. Anyways we were at a family party and i had my newborn who was fussy and needed to eat. I took him and went downstairs for some privacy so I could nurse him. This was the only area in the house I shouldn’t have had people walking in on me, but it’s grandmas fancy couches. I should have known better but I didn’t want to go sit out in my car or hog the bathroom. Anyways my sister in law comes down and plops down on the couch by me and announces she’s keeping me company, doesn’t ask or anything just takes up residence. So my letdown is super strong and it makes my baby choke a bit so I have to stop often and burp. Well he spits up and I was horrified it was going to get on grandmas fancy couches (if I’m being honest her entire house feels like a no-no room) so in my attempt to keep it from getting it on her couch or carpet I got it on his face and a bit went up his nose. I immediately cleaned him up, made sure his nose was clear and that he was taken care of. But my sister in law laughed at me so hard and completely made fun of what an awkward mom I am because I “shoved spit-up in my babies face” I was completely mortified. I didn’t even finish nursing I just let that be a snack for him and went back to the party. Well she went and announced to EVERYONE what I had done - aunts, uncles, cousins. And to make it worse, just as I suspected Grandmas only concern was “did I get any on the couch”. The only ones that laughed were my mother in law and a few of the cousins but it was still so embarrassing.

So now i absolutely hate to be around them, she still brings it up and I literally plan our get togethers around the small window of time when he’s not nursing and not napping. They keep getting angry because they “don’t get much time with him” but I just want to die every time they bring it up. Am I wrong?? Am I being too sensitive?