You know, I'm pregnant with my second, and my daughter will be just a few days shy of 2 when the new baby comes. And, rather than worrying that I'll scar her with a new addition to the family, I'm really more sad that she won't remember our special time together when it was just her and daddy and me.
I say that, because it's unlikely (though, not entirely impossible) that your daughter will have any memory of the baby ever NOT being there. She'll definitely need some time to adapt, and some alone time with you, but she'll be fine.
At least, that's what I keep telling myself.
I also was worried about loving this new baby as much as I love my little girl. In my house growing up (I realized in therapy that I never called it "home" - it was always the "house") my mom "chose" my brother and my dad "chose" me. Growing up, there were times I seriously wondered if my mom didn't love me as much as my brother or even her "kids" at school. As a mom, I know that's not the case.
And, as this baby grows and gets closer to coming to his new home, I'm already feeling emotions for it that I never did with my daughter until she was at least a month old. I KNOW what those feelings are now, I know that heart-hurting, overwhelming LOVE and I know I'll feel the same way for this new little one and that it won't ever change my heart-hurting, overwhelming LOVE for my first, either.