Scared Caregiver

I am the caregiver of my cousin. She has lung cancer that has metastisized to her brain, bone, and adrenal glands. At first I didn't feel the effects of her illness. She developed a tissue-eating bacteria that ate away at a good portion of her upper thigh, and she developed diabetes. It was August when she was diagnosed. I'm starting to feel overwhelmed, scared, and a little depressed. I see the progression of the disease right before my eyes and it's eating away at me. She's in stage IV of the disease. I feel like I'm about to lose it. Not only is she my cousing, but also one of my best friends. I told her everything I wouldn't tell no one else. We are extremely close so it hurts so bad to see this happening to her. I will always be there for her no matter what, but now I need someone to be there for me and I don't feel as though I have anyone to turn to.