I'm going to make a girl cry by saying I don't like her.
I'm not sure why you want to make her cry?
I'm so over this girl. She's so nice but I don't like her.
It's fine to not like this girl, but you shouldn't try to make her cry. If you're going to tell her that you don't like her, then you should try to do it kindly and gently so you don't hurt her feelings.
I will do it anyway. I'm a depressed teenager, that's right, that's right!
Just because you are depressed doesn't give you any right to try and make someone else upset? You would hate it if someone hurt you in this way, so why do it to them? Be kind to others and maybe you'll find the help that you need from the kindness they return.