Welcome, again, Harper, to PC. I'm sorry about the circumstances that bring you here though.

Depression is a medical illness. How long has it been since your spouse has had a complete physical? Is there a medical doctor that she trusts, that she will disclose her depression to?

I think you might be right when you say she's depressed because she hates herself. But it can be a vicious cycle. Anger is often at the root of depression. Being angry at oneself, hating oneself, can being the cycle. It's rarely one thing though, as you implied.

You do well to continue to gently counter any of her errant thinkings. There's a list of 10 basic cognitive distortions at the top of the Psychotherapy Forum. CBT (cognitive behavior therapy) IMO, is a must to help depressed people learn to counter their thinking.

Depression tells the person lies, about everything and everyone. She can't help it without learning how to counter those lies, and begin to climb up out of the darkness.

Good wishes!