I know exactly what you're going through. This also happened to my mother about 10 years ago and I'm happy to report she is cancer free. She found a lump on her breast and upon examination, the doctor found another lump. The lump the doctor found proved to be cancer. This hit our family like a ton of bricks. I am the youngest of 3 and kind of a momma's girl. I went into quite a deep depression after the initial diagnosis. I couldn't imagine my life without my mom in it.
She ended up having a lumpectomy and they had to go in twice to remove more tissue. They also removed 25 lymph nodes, which is quite a bit. She has to be very careful when flying or at high altitudes and wears a sleeve to help prevent lymphodema. She took Tomaxafin for 5 years and is currently on a different medication (can't remember the name). Her doctor told her just recently that she can go off of it too if she wants. She is very good about doing her routine breast checks and mammograms now, and strongly encourages us girls in the family to do them as well. Currently, I am waiting for results of a biopsy that was done yesterday on a lump I found. I am just grateful that she is still around to support me.
My best advice to you is just be there for her. She will need all the support she can get at this time. It's okay to cry together, but also be her cheerleader. Maybe offer to go to some of her appointments with her if that's possible. It's always good to have two sets of ears when talking to the doctor.
Take care and please keep us posted.
Thanks for your sharing...I will keep you and your family in my thoughts.