I want to file a retaliation suit against my employer after taking away 23% of my income for speaking up about a fellow coworkers unfair pay rate.

I want to file a retaliation suit against my employer after taking away 23% of my income for speaking up about a fellow coworkers unfair pay rate.
I was merely trying to help my coworker by pointing out that all other nurses in the department were making at least $10/hr more than she was. About 2-3 wks after bringing this to the attention of administration I was called to a meeting and told that while looking into this issue it was discovered that I was being overpaid and should actually be making what the lower paid coworker was making and that they would be reducing my pay to that rate. I was stunned to say the least. I feel that this is in direct retaliation for my bringing this issue to the table as well as a way for administration to justify not giving the other coworker an increase in her hourly rate.
I am essentially being forced from my position with this large of a decrease in salary; and each week-by-week attempt I have made to discuss this with upper management has been met with the same line of "I will get back with you" however I never receive feedback and am being completely ignored. I feel as though they are just waiting for my resignation. I also want to state that I have never received anything in writing about this planned pay reduction, only a verbal notice. I have already received the first of a 2 part decrease, the next scheduled for the following month.
What should I do here? Was I protected in my actions of discussing pay in the workplace and therefore now being retaliated against?

Thank you for your time