There was definitely a divide between Catholics and non-Catholics. I had a boyfriend once that wasn’t a Catholic and the community hated our relationship. I don’t remember Catholics saying anything bad about non-Catholics - it was the other way around.
I didn’t go to the Catholic school though. I really didn’t want to go to the Catholic school and I used to hide when the priest came for me. But I took instruction to be Catholic and did Holy Communion. My priest refused to have me confirmed because I wasn’t at the Catholic school.