Am I a bad person for catfishing my ex?
What do you expect to achieve by catfishing your ex?
Because he was my ex-best friend, but now I want to get back at him.
It is cruel and unkind to catfish someone online. Even if things ended badly between you and your friend, you should not trick them online. It is malicious and will only end in hurt feelings.
Whatever. I don't think it's that big a deal.
It is a big deal when you waste someone's time by luring them into a relationship that doesn't exist. How would you like it if the roles were reversed. You need to stop wasting his and your time and constructively focus on yourself and your future.