My(18m) best friend(18f) is on a severe mental decline. She has been since September 2020. In that time she has gone through many phases of self harm, a suicide attempt, and on many occasions has threatened to kill herself. Once she even did the phone call equivalent of a suicide note.

With her mental health decline she has fallen into hopelessness and now she only says negative things about herself like "I'm worthless", "I'm a fuck up", etc. She struggles with many issues like depression, anxiety, ADHD-C, ED, etc. So the problems range from trying to get her to eat at least once a day, to help her sleep, to not OD on caffeine and just her not completely giving up on her well-being.

I have tried virtually everything I can to help. I put my life on hold to try and help her for about 4 months, I helped her get a therapist, my family and I have offered her our home as a save haven and much more at my own expense.

I care for her and love her but now it's to a point where everytime she has a breakdown or crisis, she claims her existence is worthless and when I try and talk to her she deflects what I say and is at times belittling me or insulting me. At first I played it to her mental health struggles but now it's pretty hurtful and rude. When talking to her she has a lot of "demands" like not yelling, or using certain words, or not taking xyz approach. I have been trying to accommodate her for so long and it seems like each time the rules are different or that I said something a wrong way and so that I don't actually care.

Everyone from my family to my therapist say that I should cut her off or that I should call EMS when she is at suicide risk or threatening to hurt herself. I know that past the mental health issues she is a good kind person. I don't want to cut her off and the only issue with calling 911 is that she says she will kill herself before she'll let them get ahold of her (she is deftly terrified of law enforcement and mental health institutions).

I have put my life on hold enough and want to help her. I try tell her that her talent and character are good and that there is a lot to life but she only focuses on her mistakes and sees that her failing college and the pandemic have become reason enough to end her life. What should I do?

Tldr: Best friend mental health decline, she has lost hope in living and "doesn't want to be here anymore". I have done all I can what now?