Dear Starkfull,
I'm so sorry your friend is suffering. I am also sorry that it weighs upon you. You are such a good friend to care so much. Many people, including me have been helped by medication. Is that something your friend has already tried? I wish I knew what to say that would be helpful but sadly I am at a loss. I sure hope your friend finds effective care.
Sincerely yours, Yao Wen