What now?

[spearsfm]

So I am trying to keep everything confidential as this situation just happened today. Last Friday I was drug tested at my job as part of my facilities pre-employment drug screening(I have been working at this company for 2 yrs however a new contract company took over making us all new hires). However, I hate to admit but I had smoked marijuana with a friend for her birthday the week before. I was under assumption that the drug screening had been completed even though I had not taken mine yet based on the fact that I'm only part time and am only there 2 days a week. I confided in the DON (who is also a personal friend outside of work) about my dilemma and he gave me some helpful advice but also said that he had to report our discussion that we had, which I was ok with. So today while pouring my meds for med pass, I get a called from my other manager to come into his office and write a Staten about the conversation between the DON and myself;I also had my union rep with me. After writing my statement, my Manager reads it, tells me to hand in my keys and badge, and that I can no longer work until my results come back. I was devastated bit kept my composure as I left the building and walked to my car. I definitely know my results are going to come back positive but I am just wondering whether I should just put my 2 weeks in to avoid having to explain myself to the head boss, or should I let it ride it since it is a first time situation that occurred since becoming a nurse. I fully own up to what I did but cannot go back and change a thing which is why I'm considering just putting in my resignation and moving on. I'm also concerned about possibly having my situation reported to my BON. I'm just so confused and stressed out and just needed to vent.