Emotional reaction to childs illness-did i do the wrong thing?

one of my closest friends called to tell me her daughter has been diagnosed with a serious illness that will shorten her lifespan.she will probably die b4 age 30,unless science comes up with better treatments or a cure in that time.i burst into tears,told her i was sorry she had to go thru this,and that she doesnt deserve it.(shes had a series of bad medical diagnoses in her family recently-rare genetic things she didnt even kno ran in her family,as her mothers adoption records were sealed,and she doesnt know half her biological family or what illnesses they may have had.)anyway,my friend greeted my outburst in complete silence.i pulled myself together and said"sorry,i got a bit emotional.'she then resumed the conversation to happier things as if nothing happened,and i followed her lead.however,now i feel like a bad friend.i totally get she doesnt want to talk about it.did i act like a freak?i was just in shock!now i feel strange to see her,i feel ashamed of my reaction,but its a human reaction isnt it?it only lasted a minute.i will listen and support her any way i can.she has probly cried and made her peace with it and cant take anyone elses emotional reactions-i understand that.but now i feel uncomfortable,as if i was a bad friend,or did a bad thing,but that was my honest reaction to hearing my friends child might die.was i wrong?should i apologise again or never mention it-i am afraid of making another mistake.any advice,maybe from people who have "been there"?i want to do whats right,i feel i messed up-i didnt want to upset her anymore than she already is,but im an emotional person-who can think of the death of a child without being shocked to tears at the news-was i wrong?how can i make this better? ps-i put htis under family as we have known each other forever,shes like a sister to me.