I am sorry they have found a adenoma. You say you are getting sicker (i obviously do not know what your symptoms are), have you spoken to your doctor or the endocrinology department about your symptoms and concerns? If not please do as they are much better equipped than Internet to help come up with a plan.

I can't help with cost too have it removed privately. However I do have personal experience with an adrenal adenoma so can help some with the tests they do.  The CT they do is usually enough to say if it's cancer as they can look at the shape, thickness,etc of the adenoma wall/casing to check for the characteristics of each adenoma type. So if they think it's cancer or they are unsure then they would tell you straight away when they find out so they can do different scan.

If it's not cancerous then they will think about the size of it. But usually they will start checking to see if it's a functional adenoma, which is where the adenoma is affecting the hormones that the adrenal gland is producing. They do this by blood tests and also they usually do a 24hr urine collection test to check the levels of cortisol or aldosterone that your body secretes. Which is where you go home and for 24hrs you wee into special collection bottles then give them back to the hospital the next day. If it is a functional one or if its not functional but too large or in a awkward area that may cause complications then they might discuss removal. 

If they it's not functional, not large snd/or its position is not going to cause problems they may decide it's best to leave it alone. Especially as removal of an adrenal adenoma can be tricky and cause it's own complications. You can live happily with a non-functional adenoma (4 years so far without a problem). 

I hope some of that helps and that you can get answers from your doctors. Good luck.