PE bench press problem?

So I'm a girl freshman in highschool and I'm 5'2 and weigh 75 pounds. I'm underweight to say the least. Anyways, my pe teacher, aka the head football coach, is obsessed with the weight room. He is one of those buff guys who never smiles, calls people dumbasses, and expects everyone to lift weights. So tomorrow, we get tested on how much we can bench and to be honest, I can't even bench the bar, which is 45 pound. I know I'm weak but my grade literally revolves around how much we can bench. I don't want to be embarrassed tomorrow and be the weak girl who can't bench the bar. Should I talk to him? What should I do? I try in his class and I try to do the work. During the workout, I bench the bar with the help of my friends, so I'm not one of those girls who stand in the corner doing nothing. If you were me what would you do?