Deleted a FB friend and now she's asking why

This girl I use to work with was FB friends with me. We disagreed on lots of different issues that I considered important. I moved away and got another job but we kept in touch via FB (we had kids in each other's classes). I posted on FB how some states are teaching sex Ed in kindergarten, which I'm not cool with my son learning about everything until he matures. She disagrees and that's fine but I deleted her because I relied we had nothing in common but being former teachers of each other's children. She messaged me and ask why, is an explanation required?