Daughter is behaving irrationally

My daughter is 20 years old and studying in college. She has been behaving very strangely the last 1 to 1.5 years. She was involved with a boy in her college and had many fights with him. Multiple times to she took overdose of medicines like paracetamol to "teach" him a lesson. Once we even had to admit her to hospital because she took an overdose. Recently she says she has broken off with him, but now she has started behaving in a terrible manner with me. She accuses me constantly of not loving her and favouring my younger son. She claims to hate him. For the slightest reason she starts screaming and behaving in a violent manner. Threatens to end her life. I tried to convince her to go for counselling - she went a few time and says that does not help. Now she has stopped going. I am worried about 2 things: - That she will try to commit suicide - When she attempt to commit suicide, she will blame me/someone from the family, What can I do to safeguard her? What can I do to safeguard myself and other family members from false accusations?