depression?

So my friend says she has depression, but she hasn't been diagnosed. She also doesn't /want/ to be diagnosed. She's always complaining and saying things like "I'm gonna kms lol." 
The thing is, I have been diagnosed. It makes me super depressed when she talks like this, even if I'm on meds. Sometimes I think she fakes it because she sometimes laughs at me when I say things about my own depression. What do I do about this?