FIRST NUMBER ONE ASAP YOU MUST:
Freeze your credit report. Report your identity stolen with the 3 credit bureaus. Someone left a link already. But lock it up with a password. If you need to apply for credit, you have to unlock your credit report for the day you know your credit will be checked. Then no one can apply for credit in your name. If you apply for school or mortgage, leases, cards.... etc... you won't get what you want unless you unlock your credit on the specific days they call it up. It's a pain in the a... I know...
Call SS admin and report your identity stolen. Funny thing... the SS Admin knows that your identity is in 2 different places, but can't do anything to tell you due to privacy laws. I suggest... tell on your friend, and deny deny deny everything! He found your stuff in your mail or in your house, but not from your mouth! I wonder if you can get a new SS # and cancel the old one? Never hurts to ask. Probably not though.
Contact your bank. Get a NEW bank account with a password protection on it.
Also, go to the police station locally, and file a complaint against him. Ask them if this is a law broken that they will pursue or if you have to do it yourself. ie "press charges".
Also, sue him in small claims court for the money he stole, plus damages to your credit, plus pain and suffering plus anything you can think of, and make him pay you the maximum $$$ you can sue for in small claims court. $2000? or $5000? Either one... In Small Claims Court... no one is allowed to have a lawyer, and you represent yourself. The judge hears both sides and quickly makes a decision. No one gets a chance to argue, but it's worth it because as long as you DENY EVERYTHING, no one will know, and you take it to the grave with you. You've been vicimized regardless of your participation. Your identity in this country is all you have, and when someone takes that... they take YOU. Also... get your money back. Bring all bank records and employment records showing everything he did on the exact day he did it.
Go to his work when he isn't there, and talk to his employer telling them that he stole your identity and is working under your name and SS#. They will deal with it. Tell them that their papers need to change asap or you will press charges against their business. (Follow up) All these things are a pain in the a.. but these are the consequences to your actions.
Good luck.... Just DENY EVERYTHING!