Telling family

Okay so this is my second and my first me and the oh kept to ourself till 20 weeks.. My family were happy after there got over the shock but after my ds was born my sisters told me time after time she doesnt want another to be a 'auntie' too! Now both my auntie and gran have said there want me to have another and my mums abit of both! Im so scared to tell y sister incase she hates me! Me and my oh both wanted this! Best ideas, to break the news lightly?!