Sorry, no more crystal ball in this forum. It was overworked and shattered.
However, if and when the police contact you, do not speak to them and do not volunteer any information. Do not try to explain anything to them and do not go to the station for an interview!
I don't know how I can make you understand how important this is, other than state one more time,
"DO NOT SPEAK TO THE POLICE ABOUT THIS INCIDENT"
If they want to talk to you, simply tell them no, you have nothing to say. Have them go through your lawyer if they want to contact you.
They may not have enough evidence to arrest you at this point, but if you volunteer any information or speak to them about this situation, they will then have all they need to arrest you.
There is a thread on this subject that I will try to dig up and post the link for you. Then you can read what happened to someone else who didn't take this advice and did speak to the police.
Do not make any more arrangements for someone to buy drugs. Refuse to have anything to do with drugs even if it is your own mother who asks.
Here's the link you need to read:
https://forum.freeadvice.com/drug-charges-28/possible-prescription-forgery-help-423918.html