My sister has bronchitis, how can I keep from getting sick from her?

I have Cystic Fibrosis, I have a twin sister (a fraternal twin) who doesn't have the disease, but she currently has bronchitis and has a flu. I'm afraid I'm going to get sick from her. I have gotten infections too many times on my own because of my disease and was recently in the hospital and I don't want to get sick again soon, my lungs are very weak. What can I do to keep from getting sick from her? We're teenagers, and of course we live in the same house, we even share the same room.