*Sigh* I'm hearing you. I am trying to keep myself together well enough to keep my job. There's a fogginess about my thinking and it is a constant effort to keep focused on anything. Timetabling myself is hard. Remembering appointments is impossible. Multi-tasking is a thing of the past. I hardly know myself. I was considering doing a PhD before I got breast cancer and now I am so glad I didn't start it. I would never have completed it. These days I wake up wondering what day it is and where I am. I'm disoriented a lot of the time.
It's good that you had the option of deferring. I hope some time and rest allows your body and mind to recover somewhat. You can always come back to it if you feel motivated, or you can leave it and move on to other things in your life if you no longer feel motivated. So much changes in our lives that we don't always have the same goals.