She needs consequences to her behavior, no TV no computer, if she does without something she really likes she may think twice. Do not give way..It does sound as if she is out of control when she threatens to kill herself, and some therapy does sound a good idea .
Yes. This week, I'd say. You're yelling all day, is enough of a reason. You need to work on the entire dynamic and a therapist will be a big, big help. Good luck, you'll get past this, it will take work and time but it can get better.