GP found another in armpit and said doesn’t look good to have a second in a different place, likely cancer given he is at high risk for cancer recurrence.
I can absolutely promise you that no GP would diagnose 'cancer' out loud in these circumstances. Being referred for further test and getting the appointment through within fourteen days is the earliest sign of a diagnosis of cancer that anyone will ever get, because all cancer refers are to be seen within fourteen days.
As PP have pointed out, if he is using this to claim to be dying he is absolutely jumping to conclusions. A swollen lymph gland, even two, might indeed require tests but it is not a confirmed diagnoses of terminal cancer
If it were not so sad, it would be laughable.
I've now caught up with the rest of the thread, and agree that it is indeed 'wild hyperbole' I'm sorry he is putting you through this, it is absolutely a continuation of abuse. Good to know he will have family around soon, so that you can focus on your DC without a second thought.
That boundary exercise sounds great, have you have a go a drafting your answers yet.
Have you change the lock, or at least the barrel of the lock, yet ? That too is a priority. Lots of videos on YouTube to explain how to do it.