Sep Agreement questions

We have been separated since Aug 2009, when I moved out. As yet, neither of us has filed anything with the court. We tried mediation last month, but no success. We have two sons: the older one is 20 yrs old and a full time university student. The younger son is 16, in high school and lives with his mother. Can we file a separation agreement with the state that simply says we are separated, proper child support is being paid, and for 2010 I will declare our older son as my dependent and file taxes as head of household, and my wife will declare our younger son and file as HofH, and we agree to leave final decisions on the issues of property settlement and alimony for the future? If that is possible, does your website have a diy form, or do we need to use an attorney? With whom does such as form get filed? Thank you.

Separation Agreements are not filed with the state. You may simply enter into an agreement with your spouse and the contract is binding and enforceable on the two of you.