My mom is going on chemo soon and I'm really scared. Help?

My mom just got diagnosed with cancer recently and is going to need chemo. I just watched the Haunting in Connecticut and the scariest part for me was when the kid with cancer starts screaming in pain in the backseat of the car because of his chemo. And it got me really scared because I have never EVER seen my mom like that. Ever. Please, tell me how to get over this. I'm so scared of what's coming up and I don't know what to do:(