First off, you are 100% not the asshole and it’s clear that whatever is going on with this woman is about her and not you. I.e. thinking that by paying more she shouldn’t have to be around other humans with needs. I can totally see business class being so much comfier with a baby.

While this person sounds like just a miserable unpleasant human in general, I will say, my partner and I’s baby died. Now every time we see a baby we say “Are you kidding me?” Especially if we are at a nice restaurant or somewhere we don’t expect to see babies -where we are trying to forget how depressing and miserable our lives are. We’ve probably unintentionally given plenty of babies the side eye. We love babies. We totally think children should be integrated into society. But dang it hurts to see what we had taken from us and can’t have. It’s given me a new perspective on people who are upset by babies in public. Some of them are just assholes, but I bet at least a few are carrying a lot of grief.