My daughter is an introvert with suicidal thoughts. How to help her?

Hi doctor,

I have a daughter who is 19 years old. Her behavior is different now when compared to her childhood days. She had been an introvert. She is too emotional and over thinks a lot. From her childhood, she is having suicidal thoughts. She is suffering from depression for the past four years. She takes too much stress. Everything around her affects her very deeply. She has been sexually molested many times in her childhood and teenage as well. I tried to console her. But, she does not forget anything and always acts fearfully outside. She is becoming an anti-social person and suffers from poor health. Her studies are also affected. I really want to help her to get out of this. Please show me some ways. She is very short tempered. Sometimes she acts as the happiest person on the earth and sometimes she is the saddest soul. She never shares her thoughts and feelings with anyone. Our family situations are not good. There is no harmony, no understanding, frequent fights among the family members. Seeing all this she wants to go to some other city for her further studies. She says she does not like all these and she feels us as an extra headache.