Real threat or cry for help?

My daughter( 41) has had problems with drugs and alcohol since 16. At times things go good, but for the last 6-8 years the drinking is worse. We have always had a conflicting relationship, and have physically fought, slapped or pushed, not full out fighting. Recently, I thought she was finally really making an effort to stop and we seemed to be getting along. One day she called crying that her boyfriend was acting goofy and yelling (another ongoing problem at times) and she couldnt stand it any more. I suggested she and my granddaught (14) pack some things and come to my house for a few days. She didnt have gas money but I told her I had some at home and she could get it to fill up her car right away and come to my friends house, since they were on vacation. instead she came to my house, took the money and never called me back. I then texted her to never ask me for something again. The money issue is ANOTHER problem Two days later I was picking up my granddaughter to stay with me for a few days and when I came into the house my daughter screamed at me to get out of her house. I said I was only there to get my grand and wasnt there for her, my daughter. She then said "get the f... out or I'll come in that kitchen and get a knife and stab you, bitch" I stayed facing the door so if she really did come towards me I was prepared, but she then went into her bedroom, yelling something. This has now escalated way too far. I dont know what to do. I am also afraid that she may really lose it and hurt someone or herself, but I don't want to overreact and take any legal action that I would regret HELP!!