I broke someone's heart
That doesn't sound very kind, why would you break their heart?
I find them to be a wicked and ugly person.
You should not call names or  hurt them if you dont love them. If you love them just say it politely, no need to be rude to them.
I wasn't mean, I made sure to tell them exactly why I didn't want to be with them.
I'm glad that you weren't mean about ending things with them despite your personal feelings. Sometimes relationships run their course and you learn that you no longer care for a person.