I don't have much for advice, but I am a BS who has been abandoned after a 20 year marriage. I, too, suffered depression but admitted it and also lupus and chronic arthritis. For a long, long while, STBXH was my lifeline and when he had his own life's hardships, instead of working with me together, he turned on me.
I understand that you aren't having hardships maybe as he was-job loss, insecurity and so on-but I can tell you that as the abandoned spouse, I may never recover fully, nor our child.
It's only been four months since I learned the real reasons for the change in him-OW-and my life and mind are forever changed. He is already very annoyed that I am not healing faster and was that way during false R the very first week.
I am sooo glad to hear you questioning your thoughts, FS, for it means you have a conscience about leaving and that it's wrong. FWIW, I will wish forever that he talked to me -he never told me about OW, he snuck out in the middle of the night twice and slammed the door in my face twice-I don't know how your wife feels about you, of course, but for me, it has messed up my mind and blackened my heart for a very long time.
You see, one thing that I struggle with for myself and child is that he is the only one who had a choice and chose to ruin our lives without even letting us know face to face. I have never known such pain and I have never known such a sense of entitlement and such a jerk as he's become, now that he is away from me physically.
He hides behind electronics and cannot face me and bullies now.
Sorry for my long-winded story, but if you do have real caring for your wife at all that's left, I beseech you to really think.
And yes, the posts that ask if you've had counseling yourself, I agree with.
One thing that's happened here and with another family I know is that the husbands abandoned their families and do you know what? Years later, they are not happy, my ex included. Changing the people in our lives doesn't seem like it works other than a bandaid and for the other people it affects, it can alter their minds and hearts forever.
Yes, by being human you certainly have a "right" and in my mind, aren't any more bound because she has depression. Have you tried to engage her at all in special interests or maybe you have already?
My ex stopped doing that and it compounded my difficult feelings, for what it's worth to share that.