It's okay to be scared. It's okay to be filled with mixed feelings. As much as people try and shove the "be happy it's a blessing" stuff down your throat, you may not always feel that way and that is 100 percent okay.
That being said, you might want to try to start learning how to not wig out at every little thing, because it'll go easier on you once they get here.
Because you WILL learn how not to wig out, even if the the universe has to beat it out of you. That's one of the very real blessings of having twins. Honestly, now, 4 years out I am FAR FAR more relaxed and able to "be in the moment" now than I was pre-twins, and I credit them for that.
Will you get extra comments? Yeah, especially when they're babies, not so much as they get older. And really, in the obnoxious comment department you really can't win. No matter what kind of child or children you have, how crunchy or mainstream you are, ect. there will always be plenty of people who will find fault or delight in telling you horrific stories. You'd be getting them even with one, trust me.
Just keep reading around the other boards at MDC, and you will see jaw droppingly obtuse commentary by strangers to other board members who don't have twins.
Sometimes life with twins means learning to have faith without certainty, to have joy in the midst of the unknown and unexpected.
But don't let people make you feel like a freak if you're not dancing through flowery fields and farting rainbows right after you find out you're having twins. What you're feeling is normal. Learning how to relax now, how to reach out for help and support now, that's something that's important. I found meditation to be very helpful, as well as my (very mainstream but lovable) mothers of twins club.