Welcome @jepthah ,
You have come to the right place to find information and seek support. My mother had breast cancer, lumpectomy and chemo/radiation. It was a tough journey but she conquered the cancer thanks to grace and all the marvelous medical treatments available. If you don't mind, I would like to introduce you to @auntieoakley who has personal experience and insights on this.
It's easy to anticipate the worst possible outcomes, and my two cents, for what it's worth, is let yourself think about it, but don't stay there long. A positive attitude will help you help yourself and your wife. She needs all the support she can get, and in my experience going thru this with my mom and dad...our hospital oncology department had group support meetings for the patient and the caregiver. You stated you work in healthcare. Do you know if this is available in your hospital? Do you or your wife have mutual friends or family that have gone thru breast cancer that you can talk to? Feel free to look around this site on the Breast Cancer support group. There are other men that have posted your same concerns.