Well, poop on them then. I'm over the moon excited for you. Want my phone number nd you can call me and I'll pretend to be your sister instead of some weirdo Internet stranger?! Lol! But seriously, I'm so fucking excited for you.
When I told my sister about DD, I said "You're going to be an aunt!" Then there was about 30-45 seconds of silence, she said "I need some time to process this" and hung up on me. It totally sucked, but she's a great aunt now and adores DD and DS. Sorry you had to deal with that.
My dad and step-mom were excited but my younger sister wasn't at all. She posted on FB how not excited she was to be an aunt. She told her friends that I was making the biggest and worst mistake of my life. I still have a hard time talking to her.