I plan to let others know that my friend is completely responsible for my dog become pregnant.
Why blame your friend for your dog getting pregnant?
He was the person who decided it was ok for my dog to roam the neighborhood all night.
Don't blame him. This is just an inconvenient situation no one could have foresaw.
I want to hurt him emotionally and punish him for being a bad friend.
Just know that it is still your dog. Just because your friend let the dog out does not mean it was entirely his fault. Your dog should be taken care of by you, so in the end it is still you who made the decision to trust your friend to take care of your pet.