MODS - I am not trying to take this away from a legal discussion and make it a moral/ethical one. My point of bringing up all the moral and ethical points is to give perspective to how the cops most likely will view the OP. So please if you are going to edit this post at least leave the basic premise of the ethical and moral stand's I make.
OP - Just to reiterate what I believe you are saying - You sold oxy to someone who turned out to be a cop. The cop takes you to the car and takes your money and you sign a forfeit for the money. Was that all that was? A paper saying "i give these cops permission to take my money" and nothing else to it? Was it linked to a police report and any info on you already admitting to becoming an informant?
Before or after giving this money away, you tell the cops your hook up
X) and then they say if you become an informant they will make a deal with you to help you get off easier if you cooperate. To do this you need to go to court and fill out paperwork related to becoming an informant. In addition you need to put all your trust and hope in these cops that they will stay true to their word and will not just say forget the informant idea and bust your dealer that you ratted on and also bust you for all you're worth.
They already got what they wanted from you for free, you selling the drug to them and you tell them who you got it from and where he gets it from; the pharmacist employee is one, the other is the pharmacist/hospital itself. They will at least get some flack from this because a pharmacist employee shouldn't be easily able to obtain illegal drugs at all let alone in a quantity to deal it from.
[edited]
Cops don't see anything special in you. They see another drug dealer that fucked up and they used tactics
that they are trained to use to get as much info out of you for free as they possibly can, typically in most cases by using lots of fear. You get a lawyer and you are going to go down hard. Like the cops even said they won't be on your side if this happens. And since it will be your voice vs. theirs, they will win since they have all the evidence they need against you - a sale to an undercover.
Furthermore they have close to the same evidence against some compassionate person who's life you decided to ruin. If your dealer really has been getting his supply from the pharmacy he works at, he will very likely get caught. They have numerous check's and balances in place to be able to track down discrepancies and the few way's that you can circumvent these are easy to hone in on and become more aggressive if they suspect to catch someone. In this case they even know who to suspect, the person you narc'd probably already has enough evidence against him to put him behind bars. They are just going to play you out until the end, probably gathering more evidence/monitoring on who you ratted and will move onto them next.
So say you bring up the person you ratted out in court as evidence that you cooperated as an informant, and in turn should be let off of the offense against you. Think about what they can do to counter this. They have all the power and you have none, and to trust a cop who is trying to do a big part of his job - catching drug dealers and their purchasers. So far they caught the purchaser who has given away the dealer and also his money, all without any fight or hassle. Why not go after both of you with everything they have and the benefits it will give towards their job? Just like any other job, when you do what is asked of you and do it well you move forward. Making a suspected dealer turned purchaser an informants and not actually convicting them for the crime they committed only makes sense in the law enforcement career if it greatly helps them. This help comes from the amount and validity of information you are able and willing to give out.
In other words, unless they feel you could give more people away and mess up their lives too, the alternative is to just hit you with everything they got and use your scared rambling talk in the car as more evidence to go after the dealer also with everything they got. Which most likely will be months and months of monitoring/spying by the local law enforcement's tactical narcotic's team and detectives inside and outside the team. This is in hopes that they can catch any purchasers or possible dealers from the poor soul you ratted on.
They could bust you for the whole crime
[edited, sorry]. The person you ratted, you are taking someone's career and life and destroying that. This person had the compassion to give you a drug you are hooked on in a time of need because your insurance ran out.
I am on a narcotic a little stronger than Oxycontin and I understand how horrible the withdrawal's can be, it's hell on earth. You were facing this and this person had the heart to risk his job and his life's further opportunities (even though at the time you probably played "such a good friend" that this didn't really come to mind - like i'm sure he'll wish it had in retrospect) to help you out.
Maybe it's because he had the understanding and compassion and sympathy that most people wouldn't for someone facing your future of being without your scripts. I've faced it many many times, and some people have been angels in my life and go the extra mile to do what they can to not have me suffer. I have a severe back problem and pain from a botched surgery at 15 yrs old that tried to fix a bone deformity. I have been on heavy narcotics for a long time because of it. I don't sell them, i just take to much of the amount prescribed to me sometimes because of the severity of the pain. People help me out in these times. I had a time not to long ago like you were I ran out of insurance and had a loving friend give me enough opies to make a logical taper regimen. They even came over and dispensed the day's worth so I wouldn't have so much craving with it not even being available. And the anger I have knowing that their are the people like you that will turn around and ruin their lives for it.
These cops don't see it this way, and apparently neither do you with the actions you've already taken and the ones you plan to take for the good of you and your family. And you would rather put your trust into the cops, the one's who have all the power to destroy your special life w/kids and job (like the power they will use when they destroy the life of the guy with a career at a pharmacy, probably went to college to get into that career, who knows might have a wife and kids JUST LIKE YOU).
I am not trying to take this away from a legal discussion and make it a moral/ethical one. My point of bringing up all the moral and ethical points and my personal stance on the issue is one, because I am in much of the same position as the OP, and two, to give perspective to how the cops will see the OP. Why wouldn't they see you just like they see the dealer you got your stuff from? The dealer cared for your wellbeing. You couldn't care less about his. What makes you think the cops will care about yours?
From the experience of an old friend who had the same thing happen - they decide to use you as an informant (as in have you sign the papers following legal standards to label you in court as an informant and use your testimonies and call you forth) they will do this only if they really think you have a lot of valid info that they could use for evidence in convicting person/people. This evidence typically needs to be stuff they couldn't have found without you're information, otherwise what use are you to them.
In most cases informants aren't even needed in court for the conviction of people that the informant ratted out, in fact it's preferred by law enforcement and detectives that they just catch the person you narc'd on with actual evidence alone and not hearsay from a dealer/purchaser turned informant, since that holds a whole lot less validity than catching the informant's rat red handed. Also this allows you to still not be labeled in the streets as an informant, which you see as a plus just like they will. The possibility that they can catch you later on and use you as an informant all over again, since they know you could care less about anyone but yourself when it comes to doing illegal activities and will gladly drop some names of people that are hooking you up if the possibility of making this an "old bad dream" is there.
Just for advice i recommend you put this post also in the "drug culture" room or "philosophy and spirituality" and see what some people have to say about the
[position you are considering taking]. Just my 2 cents..
You say you have a family to worry about, they may be safer if you DON'T become an informant.
