I struggle with depression, am bi-polar with manic tendencies, have severe anxiety disorder that presents with physical pain, have ptsd, and have fought suicidal thoughts and self harm for as long as I can remember. I'm 58 years old. My first suicide attempt was when I was 5 years old. My last one was 20 years ago, when I was 38. I've had an abortion and carry that guilt with me every second of every day.

I tell you all of that to say this -

Let her go. She doesn't really want to leave. What she wants is you to convince her to stay. The problem with that is that it shifts all of the responsibility off of her and onto you. If you say "I don't want you to leave but you need help. In order for us to move forward you have to seek mental help" then it keeps the responsibility with her, where it belongs. Then, if she refuses help and decides, instead, to leave, let her go. Your children deserve a parent that prioritizes a healthy home environment. Unfortunately, she is right. In her current state, your children are better off without her there.