I'm going to call someone a depressed bitch.
Why would you call someone that?
Because they started the argument.
Making fun of someone else's mental health struggles is a terrible thing to do. It can be difficult to deal with something like depression, so you should not try to exacerbate the problem by making derogatory statements about it.
Do you know what's the right of free speech?
Just because you have freedom of speech doesn't mean you should say whatever you want. You are harming someone else and you should instead be trying to help that person.