This is such a difficult age. I have no experience with the drug element but can relate to the other things and it is an abusive relationship, but it’s so much harder being a child and not a partner, and it’s also very very difficult to talk about it to anyone in real life.
Can she go and live with her dad for a while, this is the most straightforward option if it’s available.
Don’t engage in the suicidal emotional blackmail, talk to her df and do what he did, call an ambulance if it should happen again.
If she becomes violent towards you, call the police.
Unfortunately those two options require the help of our services, but she is leaving you with little choice.
I do think you’ve reached a point where asking her to leave is the only viable option but it is hard. With regards to the living at home, Is she contributing at all. Don’t make life easy for her, she should be providing and preparing her meals etc, if she breaking your crockery lock it away and just leave her with plastic stuff, don’t provide food etc, she’s 19 she should be self sufficient. Are you paying for phone contracts, if so stop, don’t allow access to WiFi.
Give her the option in engaging with a gp our young minds, but I fear you will be shut down before you get the sentence out.
Good luck, all we want to do is protect them but by the time they hit adulthood when they act like this you have to take step back.
Does she have her nice times?