Just found out... and heartbroken.

Yesterday I was at my home cooking when I received a text message from a very good friend of my mother. When I opened it my heart just sank. The message read "Please pray for your mom, she is having surgery Monday morning to remove one of her breast" Immediately I called this person back thinking it was some kind of cruel joke on his part. To my surprise it was not. I began questioning him and had come to find out that my mother had been undergoing chemotherapy for the last four months because her breast cancer had come back and was now to go under surgery. I asked why I had not been informed of this beforehand and his response was " she asked not to tell you, but not to worry because my other family members knew as well and were supporting her". 

I was shocked to say the least and right then called my other relatives to verify all of this. To my surprise they did not know as well. My mom had lied to her friend about telling others just so he would not tell me.

I am so heartbroken and do not know what to think. I keep asking myself why she would keep this from me once again. ( A few years back she was going through the same thing and wnet through chemo and a lumpectomy and I had no idea)

The family all got together at my mothers home to show her support and get her to talk, but she denied everything and grew angry with everyone but most of all me.

I dont know what to do her surgery is this monday, she is not speaking and she has nobody to be there for her that day. Im at a loss because we have such a close relationship and once again she is refusing any help and support.

What should I do?