My Employer [pennsylvania] Slashed Our Salaries In Half Today, And Are Forcing Us To Choose Whether To Stay Or Leave Tomorrow. What Do I Do?

I've worked for this company for 4 years now, and today we were informed that "there was an error in our pay calculations" even years before that. As a result, our salary will be dropping from around $80-85k to $35-40k. After receiving this news, all of us in the department were told to think it over for the night, and then tomorrow we will be asked if we are committed to continue working, or if we would like to leave.

So here are my questions:

1. Should I choose to "leave" when asked, would that count as termination, and would I be eligible for unemployment pay?
2. Also should I choose to "leave", is there any kind of temporary health care to hold me for a period of time while I seek out a new job?
3. Is this even legal??

For some context, I personally have been unhappy there for a few months now, and some more recent changes the last few weeks have made things even tougher. [For example - we are no longer allowed to take off Monday or Friday...is THAT legal?] While I'm not excited to go job hunting, I know I can easily find another job elsewhere for more than that, although it will be more difficult to reach that higher number again.

Additionally I'm 27 years old and relatively health, although I don't want to be without healthcare for too long [if at all]. My student loans and car is paid off, I still live home with my family [who has already agreed to accommodate me through this process] and have no other debts. I have a decent amount of money saved up so I'm not worried about going without income for a month or two if it comes down to it.

Thanks for reading and offering any advice. Ultimately I'm siding towards leaving, but those other factors are important to me as well.