sometimes people say that your health is more important, and that if the other person has such heavy depression, it's kinda better to leave.

I'm not sure about that. The amount of negativity and depression I "get" from my gf is too much sometimes, and I want to get away from it.

But we also both rely on eachother a lot. Almost too much.

Saying "I don't know what she'd do without me" makes me sound like a huge dick, but it's true. I don't know what she would do without me.