handling rude people in public

I took a two hour flight with my 5 months old and he was fussy and was crying on and off. People were giving me dirty looks and one lady said why aren't u giving him milk??? He was already fed and changed and I was holding him and trying to soothe him, not ignoring his cries. I'll be taking a 17 hour flight in march and I'm very nervous about this. How do u handle people in public that are rude?