sexual harrasment

I am the [male] supervisor of 2 employees of whom are close friends of mine [1 male and 1 female]. we 3 spontaneously decided to play a joke on my manager and another employee as they were walking out of the building. we were parked in my car [off company property and off the clock] and simulated a suggestively sexual act. the only clothing that was taken off was my shirt. and we made highly exaggerated noises and rocked the car side to side. they saw us, got in the car, and left. 2 days later [today] i find our managers on a full investigation by means of interrogation of us 3 to try and make us confess that one of us came up with the idea and that we actually did have sex. the idea to do that wasnt brought up by any one person.. and we did NOT have sex. basically, they are not satisfied with the truth and wont make any decisions in regards to our inappropiate behavior punishment until one of us decides to make up a false story and claim to be the perpetrator and rapist.

is this legal? what are my rights?

can they force me to work with the other employee who saw us that night despite the fact i feel very uncomfortable in a work environment with him?
can they force the female "victim" [my best friend] to take some kind of medical exam to see whether or not she was raped/had sex. obviously she would result in negative for sex activity.
i feel like when i go into questioning tomorrow at work they will try and manipulate my words into creating a false story to incriminate myself. am i allowed to secretly record the conversation in case they threaten me? can a police officer be waiting outside my work place as a threatening symbol to intimidate me?
am i allowed a copy of every written observation/notes that they take of me while im being interrogated tomorrow?
if i were to quit on the spot, can they use that as a way of confirming my supposed "guiltyness".
sorry for all the questions!!

please respond with even the slightest general responses!