What should I do?

I am taking classes at a community college and all throughout high school I was a straight A student and my first semester at the college I got all A’s. Over summer I got my first B in public speaking and my parents freaked out, telling me I didn’t work hard enough for it and I wouldn’t get into Med school if I had a B. This semester I worked really hard but I was so stressed it affected my grades and I ended up with a B in biology and English and a C in trigonometry. I can’t tell my parents because they will just get mad at me again. I told them I got a B in trigonometry and an A in everything else. I know that they are going to find out eventually but I can’t tell them. This has made me stressed, worsen my anxiety, and made me depressed. To make it all worse, my sister is at college and she’s getting all A’s without even trying. I don’t know what to do. Should I tell them, or should I just hope they never find out?