Revenge for Best Friend who betrayed my trust?

I recently confronted my good friend Andrew and he admitted to me that he did in fact pass on several STDs to my puppy. It honestly had me shocked and angry at him and I feel as if he's betrayed me. He told me it was payback for when I crashed my car in his koi fish pond when I was wasted and told me "you and that pudgy poodle got what you deserved". I feel he's gone too far, and I can't get let him get away with this. Any suggestions on how to get my revenge on him?