Unhealthy Relationship?

It's the fact that you care about her more than anything.
It definitely seems that your girlfriend is still going through heavy amounts of trouble, and she'll need you more than ever, and as you've gone through troubles yourself, you'll need her.

You're very open to her because you've both been through dark times, but both of you together can hold on and keep going through with life.

So no, this isn't a unhealthy relationship.
No matter how bad it may seem at some point if she continues with habits, you two are very much perfect for each other.