Hello & Welcome, hwc.critchfield!
Wow. Your description of your wife's behavior makes me think she is suffering from more than just depression. Have you spoken with both your doctors and hers about what's going on?
You may have heard it all before, but you might find something you've overlooked below:
10 Ways to Help Someone with Depression PsychCentral/NIMH
4 Ways to Support Someone With Depression by Therese J. Borchard, PsychCentral
PsychCentral Caregivers Support Forum
Given you own condition, you have to be sensitive to your own limited resources in dealing with her. Active assistance from outside your family may be necessary (but even that does not guarantee success).
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My dog
mastered the "fetch" command. He would communicate he wanted something, and I would fetch it.