I'm the same as you hun, I personally don't like dogs, I'm also scared of them and just don't trust them. I would ask friends to keep their dog away if I'm round. We've been to friends when their dog hasn't been away and I just kept Tristan very close to me and turned away if the dog came near us. The owners are always very aware of their dogs and I'm sure would take measures to make you comfortable.
But I'm sure if your friends take precautions to keep him away I'm sure it wouldn't break free and you would be fine.