I was mean to the girl I love
Really now? You were mean to her? Why?
She's too nice to everyone, and she needs to learn discipline.
Feeling that you need to teach "discipline" to a partner sounds abusive to me. You shouldn't be mean to someone you say you love. Consider getting help for this issue before you do something really bad.
I'm done with her thankyouverymuch, you won't need to worry about me hurting anyone.
It's good that you left her, because she deserved better than abuse. When you love someone, abusing them is a horrible and gross act that most people despise.