But what if I don't HAVE a softer side?

I totally lost it today in class and ripped a kid up one side and down the other for lying. In front of the rest of the class. He called his mom, his mom called the principal, I got called in. His mom wants him taken out of my class. Can't say I blame her. So I apologized to the kid, apologized to the mom, explained to her why I was frustrated with her kid, and asked for a week to try and smooth things over before we move him to another class. I think it will all be fine, but the principal thinks I need to look for my softer side. Problem is, I am not sure I have one.