I can't connect with my diagnosis..

Hi there, This is my first post for 5 years. A month ago, I was diagnosed with metastatic bc in my spine and rib, 5 years almost to the day of my initial diagnosis. I am perfectly well, and it was picked up after a routine oncology check showed elevated markers in my blood. The week that my oncologist phoned me, I was completely snowed under with work and family commitments. My aunt had died whilst I was sitting with her, the day previously, and I was responsible for organising her funeral arrangements. I had a thesis proposal due in, and a critical work project about to begin. My husband was interstate, and I was playing catch up at home, having just arrived back from a European trip. It was chaotic.
Initially, I had a tiny cry and did some swearing, but then I decided that I could not afford to indulge in any kind of medical drama, and I put it aside to be dealt with later. The thing is, now that life has settled down a bit, I am having trouble even connecting with my diagnosis. It feels neither real, nor important- although my head knows that it is huge.
I have told my siblings- by text message, but advised them not to contact me because "I have no interest in discussing it right now'. I have told my 5 children ( teens) in as upbeat and dismissive a manner as possible, but cannot bring myself to tell my father. I have told my closest friends, but they are under instructions not to share the information. It is business as usual. I know that my friends and family want me to open up, but I hate drama and I despair at the idea that I will be forever considered through the lens of cancer. I feel the need to control the information, because I know that it will be dynamite to my broader family and friend group. I cannot deal with everyone's fear when I am unable to even connect with it myself. They were all so wonderfully supportive through my initial treatment, but that can be overwhelming, too. 

I suppose my question is, How did others share the diagnosis in a way which didn't feel like dropping a bomb?  Did others feel this remarkable sense of calm, and is it going to hit me like a ton of bricks?