Breastfeeding related

Hi all! I have an 18 month old boy that I breastfed for a year and we are expecting another LO in july. I wanted to breastfeed longer but due to wanting another baby I stopped so my cycle could return. My soon to be inlaws aren't very pro breastfeesing. My mother in law thinks I shouldn't allow my son to see me breastfeed and she also thinks I shouldn't breastfeed past 6 months because it's "gross". What do I say to this? I have presented her facts about breastfeeding and have tried to make her understand that I WANT my son to see it but she just isn't getting it. If you have some advice I'd love to hear it. I posted anon because I have a couple friends and inlaws who use the app and I don't want to start a huge fight about this.