1k sign on bonus repayment help

So let me start by saying I’m in MN at a hospital as a phlebotomist (the person in the hospital who collects blood). I have been here for 4 years and just recently started this job. I accepted a 1000 dollar sign on bonus at my hire date that was obviously taxed and I netted around 450 dollars after the fact. Fast forward to now and it’s horrible. People are quitting left and right and I’m stuck filling there shifts with no real choice. I was lied to upon my hire that I’d get a raise at 6 months which didn’t happen, that I wouldn’t get constantly mandated because I was willing to work overnight shifts and that they’d work with me since I’m in nursing school. I want to quit so bad. It says in the sign on contract that I have 60 days after my last day to pay it back or they MAY sue me for it. Any advice on this or do I just have to pay it back? I’m aware I was foolish to accept it without really thinking about it but they made it seem so nice and after the honeymoon phase was over it became a miserable place to work.