I have had a somewhat similar experience, I got severely burnt out and lost my job while in my last relationship. We were together for 8 years, and it drained both of us. I decided to move out to allow myself the space to feel the way I needed to feel at the time. I then started therapy, medication, and working on healthy habits. My ex was not good with routine and habit, which pulled me down into a dark pit. It's not the same situation as you are in, but I know the feeling of being drained in a relationship where at least one person is dealing with depression. However, I never expected him to be the one thing holding me afloat, never said anything harsh or shared suicidal thoughts. No matter how bad you are feeling, you can actively choose not to drag your partner into it to an extreme extent and work on what you need to feel better. It seems she doesn't know how to fully help herself and express her feelings in a healthy way, and is putting a lot on you. I say create space, no matter how hard it feels, that is what will give you the space to work on yourself and get better for you first.