I have to take Demerol and Valium before oral surgery. I'm terrified! What should I expect?

I am getting my wisdom teeth removed in a couple of weeks. I've never heard of it being done this way before, but apparently I'm supposed to get all hopped up on prescriptions before I go. According to the prescription I am to take two 50 mg tabs of Demerol. And I'm supposed to take two 5 mg tabs of Valium. Just to make it clear, 100mgs of Demerol and 10mgs of Valium. I am a 27 year old petite female,125 lbs. I am terrified of taking pills and I hate not feeling in control of myself! I am so scared of what this is going to do to me! Are these really high doses? what can I expect? I'm freaking out here!