Try to avoid becoming a police informant. They'll "work you" as long as you're useful, yet stay ambivalent regarding what you receive in return. In the long run, police will turn your file over to the prosecutor as soon as (1) you are no longer useful, and/or (2) the statute of limitations on your possible charges is close to expiring. At best, if you're a good informant, police will inform the prosecutor you were cooperative; and you might catch a downward reduction and/or dismissal of your criminal charges, if you face any. It's a dangerous gamble, especially in your circumstances. Unfortunately, the police are wary to trust you or give you a break because you've complained about a Sheriff Deputy.
You must operate from a position of strength. Consider hiring counsel. An attorney would strike clear-cut deals with prosecutors. An attorney could also argue a motion to forfeit property illegally seized from your home (your weapons). The "waiver of attorney" document you signed is not legally binding. This is especially true if you were drunk and stoned.
You should not face criminal charges for breaching the agreement (Obstructing is possible, yet still far-fetched; you have a 5th Amendment right against self-incrimination). Realize, however, that you may face underlying criminal charges if you breach the agreement. Again, a gamble. Lawyer up!