I need a lawyers input on a slander situation?

Ok here is the deal my ex girlfriend has 2 other ex boyfriends either 1 of them or someone who knows us has wrote a letter describing what it is like to date my ex. The letter is extremely vulgar and blunt although very true it describes how she used us to our sex lives to every horrible detail. They created a fake email and sent it to us and have been chatting back and forth about the letter threatening to publish it on web forums and the like when they do post it. What options do we have. Not knowing who did this would the police or could the police find out who created the email and sent this? We filed a report but they don't seem to be doing anything about it. If they could or would find out who would we have a case criminally or civilly? I would like to know if I need to light a fire under the officers *** and get him working or if the report is as far as its going to go. I live in california if that helps. I would be more then happy to discuss this farther and or send the letter in private email but will not post it here as it is extremely embarrassing and revealing to all of us. Thank you for your input.