Chris,
Just rebuild the circuit, there is a good chance the transformer is not damaged as the PCB tracks acted as your fuse. However, you were lucky this time, had you handled the low voltage side of the board you could have been electrocuted. Hopefully, your first big bang scared the xxxx out of you as it did me and you will double check everything involving mains in the future. I had a very good friend who lost his life through a silly mistake like this.
Mike.