Accidents happen - especially when there are animals in the house. I have a yellow lab who weighs in at 105 lbs and has been our only "baby" until my daughter was born. We always have to pay attention because even when my little one is squeaking a toy, the big pup comes running! What you are describing is something I ALWAYS worry about!
A few weeks ago, I was sitting on the ottoman in my daughter's room with her sitting on my lap and my dog was standing in front of us wagging his tail while I patted him. Next thing you know, he heard something outside and turned and ran - when he turned to run, the side of his face and nose bashed my little on the side of the face. There was that momentary silence and the the screaming and sobbing followed. I felt like such an idiot! All I could think was 'good moms don't let these kinds of things happen' - but let's be honest, accidents happen! We try out absolute best and that's all we can do. My daughter is infatuated with my dog and I cringe knowing that once she's crawling and walking there will be many accidental knock downs.
I feel terrible for you because you felt terrible about what happened. I'm so glad your little one is going to be ok...and you will be too!