Working up the nerve to tell my gma

I am 16 weeks today and still have yet to yell my grandmother. She is not the nicest person, and I am concerned about her reaction. My aunt is having trouble getting pregnant and is currently going thru in-vitro fertilization. One was unsuccessful but there are three more tries. I'm worried my grandmother will take my news as an insult to my aunt's struggles. I'm going to try and tell her today. 😥