I feel for you, and everything you've written -- about how much you're struggling and how bad you feel -- makes perfect sense, given that you've been through intense trauma.

Fwiw, I think that developed nations discourage people from acknowledging the intensity of their traumatic experiences, for various reasons related to consumer culture and keeping the economic machine going. But you HAVE been through trauma, and you need to be clear with yourself about that (as in, "After all I've been thru, it's logical that I can't really function well in the short term"), and kind to yourself as you gradually heal.

I'm not suggesting that you stop taking antidepressants, but they aren't the solution. An adjunct during a terrible time, yes, but not the solution. You need to be able to cry out your feelings and shriek out your feelings in a safe space, with a licensed, experienced therapist. And I wonder whether EMDR (a therapy to address trauma) could help.

Can you talk with someone at the hospital where you've received cancer care? Mine has a dedicated social worker, for ex., who has guided me toward some useful resources. And the Psychology Today website lets you search for therapists by geographic area, but keep in mind that you're better off getting a recommendation for a therapist from someone who knows, or has worked with, the therapist.

Finally, if your insurer is being a jerk and is refusing treatment that you need, call the office of one of your US senators and ask to talk to someone who handles health-care problems -- that person might be able to advocate for you.

I believe that better times are ahead for you; I believe that based on my own ups and downs for most of my life (I'm 62) and based on the reality that every living creature is built to heal. (Yeah, we all break down at some point, but I think you're not there yet.)