grr i just wrote a reply and deleated it
i said something like i am so sorry your going through this

I would be lying if i said i know what your going through or how you feel, but i do know you need help.
Do you think you can tell your sister? It maybe a very good and big start. i can't stress how much you need help, love and support from those around you, and also some medical help too
I wish i could make it better for you but i can't, so i will send some hugs and keep you in my thoughts
All my love
Vikki