Everything is scarier at 4 in the morning! I doubt if anyone ever had a really good idea when sleepless and anxious. Talk to your GP about a Psychologist or counsellor to assist but some sleeping pills (temporary) wouldn't go amiss either. We all need help at different times, that alone takes some getting used to. I was fine during chemo but found a counsellor invaluable about getting my head around what I wanted to do next. Many of us share that awful feeling - this is the end of the life I know - but so often it's just the start (OK, very abrupt and alarming) of the next part of our lives and there is much to look forward to. It will get easier, just concentrate on putting one foot in front of the other for the moment. Think of the good things in your life, don't let cancer occupy all of your thinking (it's easily done). When it gets too much, sit back and breathe deeply. One step, one breath at a time and you will get through this.
