I'm going to play devils advocate because....well I always do lol
I made my partner swear to secrecy as well - for a long time. I let her tell her family when I decided it was time. The truth? She needed them.
I wrapped my life up into having surgery. Every free day was spent at doctors appointments, making sure insurance was doing things properly, and I was completely consumed. I made life about me....and therefore I made my partners life about me too. WE focused on getting me healthy.
I didn't realize until after surgery how scared she was - How worried she was for my health and how our children would react to it. She needed people like her family to turn to in her difficult moments.
I am not saying what he did was right - because I would have been angry as well. I'm just speaking from my experiences.