Although I do my best to comfort her, I don't know what to tell her apart from "you need to move on" or "your dad was wrong, you're very successful bla bla".
The thing is, I've realized that before her breakup, she was kind of a naïve and nice girl, who would rarely if ever stand up for herself (she was "too nice"). After the breakup though, she became much more aggressive and stands up for almost anything (sometimes going overboard when she threatens people (i. e. if they continue with their behavior, she will make them pay and she lets them know about it)).
She's aware that she has changed in that regard and she isn't very proud of herself. She cries very often and calls me in the middle of the night to talk while crying.
Recently, she's been talking a lot about death and she has been giving away stuff that I know is precious to her. She didn't explicitly say she was suicidal, but I am pretty sure she is and I don't know what I can do.