My friend killed herself and im depressed?

so theres his girl, we talked alot, and she had a crush but i didn't feel the same, anyway i was there for her always and she opened up and told me how her parents tried to kill her at birth because she was a twin and her other twin died, and stuff and then their parents ended up taking their own life about last month, anyway she found out the full story, and ended up taking her own life i was talking to her 2 days ago and we were great and today i found out she got amnesia 2days in a row and she started cutting herself deeply and she killed herself, now im extremly devastated and start crying everytime i see her facebook :( what should i do she was a good friend of mine