How can I help my depressed friend? Please help it's important!?

So I'm friends with this girl (we talked a lot in school but haven't hung out outside of school) who had suicidal issues (that her parents knew about) a couple years back, and is still super depressed. But the problem is, all she ever does is complain. I have tried to change the subject, and she makes a one sentence comment, and then starts talking about her "issues" again (some of them really aren't even that bad). I really feel bad for her, and I don't want to hurt her, but it's getting to be too much. It stresses me out A LOT, and brings back bad memories from my past as I've gone through a lot of what she's going through. I don't mean to sound self centered and not care about her, but I feel I've dealt with it too long. What can I say?