Have to take a group shower in swimming cl???!!?

Hi, I am 17 and a senior in high school. We are on a block schedule, and the last schedule of my senior year is about to start (roughly, the month of may). In it, I signed up for swimming cl (sounded easy/fun). I just found out however that for swimming you are REQUIRED to shower, and that the showers are more or less communal (there are dividers but no doors/curtains). I asked my mom if I could get a note to get out of it but she said its no big deal, that she had to do this in school and that I need to get over myself. I really can't imagine having to shower like that, but I also can't change my schedule in the middle of a semester without parental permission. 1) What should I do? 2) Is this as bad as I think it is??