How can I tell my best friend without being a jerk?

I've been a little down lately and one of my best friends...well, I try to confide in her, but whenever I do she kinda pulls out the "I have more reasons to be depressed than you" card. Usually when we have this kind of convo, I usually don't complain, but try to help her talk through her problems. But, I mean, it's SO tiring and sometimes I'd wish she'd give me some advice or something. I want to tell her that, but I don't want to come off as some selfish jerk. Any suggestions?