Depression

Natalie👑 • Well, I'm Natalie. That's all
Yes this topic is common in the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> and <a href="https://play.google.com/store/apps/details?id=com.glow.android">glow app</a> community but I came not to say I'm depressed but I need advice 
My sister she has depression. And what's worse is that she's been hiding it for around two years and as a little sister I wasnt prepared for this. 
Lately she's been quite upset eating more than she usually does and she told me this recently, and I don't know  how to deal with it. 
I want to say something but I'm afraid that if I say the wrong thing then I feel like she will hate me for what I said. How can I help my sister without freaking her out?