Hi quillan68, I'm so sorry to hear about your recent health problems. I hope that the biopsies and other tests will reveal that the surgeons were able to remove the entire growth. Will you have to receive further treatment such as chemotherapy or radiation?
I have a slightly different take on the whole 'should I tell her' question. I'm not going to tell you how codependent you are to feel the way you do and to want to tell her. I certainly understand that. I'm not going to tell you that the 'least you can do' is respect her wishes, but I will say that perhaps the BEST you can do is care for yourself during this health crisis.
I'm more concerned about how you would feel if you told her (or had someone else tell her), and her reaction was no reaction or even an angry accusation that you were making it up to win her sympathy. Making yourself vulnerable to that kind of pain when you struggle with this kind of health concern could be, IMHO, detrimental to you.
Please consider focusing all your attention and energy on yourself and your healing. You will be in my thoughts and prayers.