You have rights! As an employee at will you may leave the job at any time for any or no reason. That is one of the most basic of our freedoms in this country. No one can force you to stay on the job if you'd rather leave.
As rotten as this is, management can be rude, vulgar, hypocritical, demanding, bossy etc.......
I'd suggest you assess whether you can ride out the change or whether you'd like to look for another employment opportunity.
And now an answer from a Pennsylvania attorney.
Pennsylvania is an at will state in which you can be terminated for a good reason, bad reason, or no reason at all. You cannot be terminated in violation of "Public Policy" which our courts interpret to mean statutes enacted by the U.S. Congress or the Pennsylvania Legislature. When you are terminated because of your "protected classification" (i.e. age, sex, race, national origin, disability, and in some localities gender affinity) it's called "employment discrimination," not wrongful discharge.
People discriminate every day. When you choose what to wear in the morning, you discriminate against your other clothes. When you choose a flavor of ice cream, you discriminate against all the other flavors. It's discrimination based upon "protected classifications" that's unlawful, such as discrimination based upon sex, race, age (over 40), national origin or disability.
People are not fair. (And I don't remember learning anywhere in law school or elsewhere that life was fair). While your supervisor should not bully or belittle you (it tends to reduce productivity and that ultimately reflects badly on the supervisor), so long as you are not being singled out due to your "protected classification," there is little or nothing you can do except find a job elsewhere.
Note, however, that if you do resign (instead of waiting for this abusive supervisor to fire you), you will not qualify for unemployment benefits.