I don't have metstatic disease but certainly get the overwhelming exhaustion of chemo and the feeling of just "give up now" that goes with illness and depression. And yes lovely you really are experiencing depression.
Now "talk therapy" can help when your ready. But in reality maybe it's actually time to look at an antidepressant...or dose adjustment to assist in balancing the serotinin in the brain. Once it is better you might be able to rally your inner strength to assist in recovery of your mental health.
It's been a tough year for you and very few would be able to just soldier on with a smile. Let us know how you are going. Kath x