Grats on potentially throwing away tens of thousands in student loans/grants and permanently banning yourself from said university/college.
Ya got 2 chances. First, and this is coming from a non religious person, you PRAY with all your heart to every deity you know of that the teacher uses TAs for marking and 2 different ones mark each of your tests.
And if, dread it happen, teacher calls the two of you out, you play dumb and accuse him of stealing your answers. Demand that you can, on the spot, solve any of the problems and that the other dude must have been peeking over your shoulder, or that he must have taken them from the teacher or seen them being fed into the scantron etc etc. This probably won't work, but it's your only chance. Being up front and saying he copied them will get you a zero and possibly expelled. Getting caught and then admitting it will get you a zero and PROBABLY expelled.
Good luck OP, you need it.