Can I be fired rightfully because after 45 minutes of saying no and denying accusation made against

I was recently fired from my job due to accusations made against me about using marijuana on the job. So they called me in on my day off and asked me if this was true and I denied it for forty five minutes and finally they said they had multiple statements against me so I was like done yea sure just so I could get out of there because at that point I felt interagated and was in tears and shaking. They never offered me a drug test not one time.! So they initially fired me for being under the influence at wrk. There's is no survelience at this place no security at all. I cannot receive my unemployment for the reason they have fired me. There were also two others involved one also was terminated that same day and the other lady they let finish out the rest of her week and get the rest of her deserved hours