How do i get my dog back?!?

How long has it been since the dog was sold. If the dog was yours and registered under you name you could have called the police as it was not your boyfriends dads dog to sell. So it could be seen as theif. And the buyer could have also been charged with buying stole goods. I would advice you seek legal advice it maybe that because it has been so long you might not be able to get her back as they may say you should have take legal action earlier. You couls also pop in to local police station and ask if they can still legal help. Do you still have all the texts you sent this women as that could help.