Hello and thank you for entrusting me to assist you. I am very sorry to hear about this understandably upsetting experience.
Whether or not you have any recourse depends on whether your employer had reasonable suspicion that you were using drugs. "Reasonable suspicion" can be anything from a co-worker report that you were seen using drugs, to erratic behavior, to finding drug paraphanelia. Since what constitutes reasonable suspicion is rather subjective, it is fairly easy for an employer to meet this burden, but they do need something.
If your employer had reasonable suspicion to justify the drug test, then they did not violate any law by asking you offensive questions, telling you that they would consider it a resignation if you left the room, or by escorting you out, regardless of whether this caused humiliation. If they did not have reasonable suspicion to conduct the drug test, and if you did not plainly state your intent to resign (which you didn't), then this would be an unlawful termination as it occurred in response to your refusal to submit to an illegal drug test. Employment is normally "at will," meaning it can be terminated at any time for virtually any reason true or untrue, but there are certain "public policy" exceptions to this policy, and one would be terminating an employee in retaliation for refusing to submit to an illegal drug test.
So again, any recourse you may have turns on whether your employer can prove they had reasonable suspicion to test you. If they had absolutely no reason for doing what they did, then there is a good chance you have a case. But if they have a documented reason, even if it is one you completely disagree with, it will likely constitute reasonable suspicion and you will not have any recourse for what happened.
I hope that you find this information helpful. Please do not hesitate to let me know if you have any questions or concerns regarding the above and I will be more than happy to assist you further.
If you do not require any further assistance, please be so kind as to provide a positive rating of my service so that I may receive credit for assisting you. Very best wishes moving forward.