Can they hold me liable if I spend a check that they wrongfully sent me?

I received a financial aid refund check in the mail for $3,210 from my former school. Two days later, I find out that it was a mistake. Do I have to return it? They gave it to other students by accident too but the difference is I have not been enrolled anymore since June of this year. They sent out emails asking for the money back to the other students but not to me because once again I’m not enrolled so they didn't contact me. I already deposited it in the bank.