Moms dying of cancer? Help anyone I need support?

My mom is on hospice for her cancer. The doctors told her they can't treat her cancer properly and it would be better if she was just on hospice. Since she started she's not herself. During her year of cancer she was always upbeat for her vistors and my family. Now she barely talks and doesnt know what's going on. It's so hard for me, only being 13. I never really show my feelings but today when my sister asked me how I was I burst out into tears saying how I feel so sorry for her, my dad, my siblings, my aunts and uncles...etc. My aunt was over today and she was telling me that she told her grandchildern (my 2nd cousins) about my mom and how they were crying. There 4 and 8. It's so sad and I'm going to be so lost without her. I have to go through my whole high school life without a mom. Any help?