I can't add anything useful to what the others have said @jsn other than I'm thinking of you and hope that you've been able to get a handle on this.
If not and you're unable to access counselling with the Christmas period you may want to try one of the following:
Beyond blue - Call 1300 2244 36 24 hours 7 days a week or you can chat online 3 pm – 12 am 7 days a week,
Life line Australia National 13 11 14 24 hours 7 days a week
Cancer Council Helpline 13 11 20 Operating hours will be business hours (EADT) – not weekends or public holidays.
Most of us have hit a wall at some stage but if it's so bad that you can't manage anything, it sounds like you need to talk to a professional. There is no shame in reaching out. You've been knocked about with this disease and I think sometimes that it messes with your head more than it does with your body.