Feeling overwelmed by Grandma's cancer?

My grandma has been fighting recurrent, metastatic breast cancer for over a year and a half. I'm finding myself feeling really overwhelmed by the up and down of all the treatment, scans, tests, etc. She's one of the most important people in my life. I have really good days, and then I have days where I feel like I'm on an emotional rollercoaster. Is it normal to feel this way? Anybody been through something similar? What helped you get through?