Would you be angry about this?

My husband’s family have some really odd views. They’re very southern Baptist and think things like Harry Potter and astrology is evil and of the devil. They also have some strange views about marriage/sex/child rearing. When I had my first, his grandmother told me she hopes I don’t breastfeed because “my breasts are for my husband”. My MIL told me that breastfeeding was weird and sexually deviant.

Well, I have breastfed both of my children for 2 years each. This being world breastfeeding week, I made a very sappy post about it on Facebook. My MIL and his grandmother both angry reacted it and his grandmother wrote “gross” underneath my picture of me nursing my son (NO nipple showing at all, you can just see his head).

I usually keep my mouth shut about their weird opinions but I am really angry about this. Is that not so fricken rude and unnecessary?